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 Division of Agricultural Sciences 
 UNIVERSITY OF CALIFORNIA 
 
 TERMITE CONTROL 
 
 Prevention and Control of the 
 Western Subterranean Termite 
 
 Walter Ebeling 
 Roy J. Pence 
 
 CALIFORNIA AGRICULTURAL 
 Experiment Station 
 Extension Service 
 
 CIRCULAR 469 
 
 (REVISED) 
 
TERMITES 
 
 Various castes of the western subterranean termite. All individuals are enlarged ten 
 times. 
 
 Left to right: 
 
 Prealate: Immature, wingless form. Body is white; abdomen shrinks as wings de- 
 velop. Found in subterranean colony. 
 
 Alate: Adult, winged reproductive form. Usually seen swarming in open. Black 
 bodies, light gray wings. (Unlike swarming ants, these have no slender waist.) 
 
 Primary Queen: Large body; wings were broken off after swarming. Remains in 
 the colony. 
 
 Supplementary Queen: A wingless form which never leaves the colony. Lighter 
 color than primary queen, but somewhat darker than other castes. 
 
 Soldier: White body, about *Hfi i ncn long. Head is armed with long jaws, eyeless, 
 quadrangular, about the size of the body, and light yellow in color. Soldier re- 
 mains in the colony to protect other castes from insect enemies, especially ants. 
 
 Worker: White, eyeless. Body about Vs inch long. Feeds on and destroys wood, 
 and is the most abundant form. Control measures are directed against workers. 
 
 APRIL, 1965 
 
 THE AUTHORS: 
 
 Walter Ebeling is Professor of Entomology, and Entomologist in the 
 Experiment Station, Los Angeles, and Roy J. Pence is Specialist, Depart- 
 ment of Agricultural Sciences, Los Angeles. 
 
 [2] 
 
TERMITE CONTROL 
 
 Prevention and Control of the 
 Western Subterranean Termite 
 
 Walter Ebeling • Roy J. Pence 
 
 In California the western subterranean 
 termite, Reticulitermes hesperus Banks, is 
 the species that causes the greatest dam- 
 age. Like all subterranean termites, it 
 feeds on wood but must maintain contact 
 with the ground. If feeding above ground, 
 it either burrows upward through the 
 wood, crawls through cracks or voids 
 sealed away from the outside, or proceeds 
 to food sites through earthen shelter tubes 
 which it builds. 
 
 On a warm, sunny day following rain 
 you may see the termite's winged repro- 
 ductives swarming. If you will survey the 
 area, you may find them emerging from 
 their subterranean galleries through small 
 exit holes in the ground, perhaps over a 
 buried tree stump, through cracks in the 
 slab of an earth-filled porch, terrace, or 
 patio, or from cracks and crevices in 
 buildings. 
 
 The winged individual's total length is 
 about % inch; the body, not including 
 wings, is about %e inch long. The wings 
 
 are light gray, the body black, and like 
 all termites, it is comparatively uniform 
 in width; unlike the ant, for which it is 
 often mistaken, it has no slender waist. 
 Termites are social insects; their various 
 castes are shown above. 
 
 The winged termites swarm to repro- 
 duce and found new colonies. Supplemen- 
 tary reproductives remain in the original 
 colony, and can be distinguished by their 
 lighter color and the absence of wings. 
 They have only rudimentary wing pads. 
 All other termites left behind after swarm- 
 ing are white wingless forms — reproduc- 
 tives in the prealate stage (before growing 
 wings), one or more queens, soldiers and 
 most abundantly, workers. 
 
 After their flight, a male and female 
 break off their wings near the base and 
 found a new colony. They excavate a shal- 
 low cell in the earth, usually under wood 
 or vegetation, or in the crevices or under 
 the bark of moist wood. Eggs are laid in 
 a "royal cell." Development of the pri- 
 
 [3 
 
mary colony is very slow and the first 
 generation of winged reproductives in this 
 colony cannot be expected before three or 
 four years at the very earliest. Supplemen- 
 tary queens eventually develop; these do 
 not form wings and fly away to start new 
 colonies, but they are important in build- 
 ing up the population of the primary 
 colony. 
 
 It must be borne in mind that a build- 
 ing may be infested by a large colony 
 which already existed under or near the 
 building at the time it was constructed. In 
 such a case, large numbers of termites are 
 suddenly available to attack the wood 
 structures. 
 
 Termite activity increases in warm en- 
 vironments. For this reason termites are 
 abundant in California, where climate 
 favors them. Increasing use of central 
 heating contributes to their becoming 
 more active in colder areas. Central heat- 
 ing results in greater areas in buildings 
 which are continuously kept warm, includ- 
 ing those areas in which termites do 
 damage. 
 
 Damage from drywood termites, Incisi- 
 termes minor (Hagen) (see page 14) 
 generally occurs most abundantly in the 
 upper portions of a building such as in 
 
 the attic of a house. However, sometimes 
 the damage from subterranean and dry- 
 wood termites occurs in the same general 
 area and it is useful to be able to distin- 
 guish the two types of damage. 
 
 Subterranean termites attack only the 
 soft spring growth of wood. Consequently 
 a cross section of infested timber shows 
 a characteristic radial pattern of gallery 
 or tunnel formation. This pattern can be 
 readily distinguished from that of the dry- 
 wood termites, for the latter burrow 
 across the grain of wood, as well as in the 
 same direction as the grain, excavating 
 broad pockets or chambers connected by 
 galleries about the diameter of the ter- 
 mite's body. Thus they destroy both the 
 soft spring growth and the harder sum- 
 mer growth. The characteristic tunneling 
 patterns of the two species are shown on 
 page 8. 
 
 Although you will ordinarily not do 
 your own control work, you will want to 
 understand how to recognize signs of ter- 
 mite infestation and damage; the basic 
 features of structural design that aid in 
 preventing damage; and what the termite 
 operator can do to protect your home 
 from termite damage. 
 
 Signs of Termite Damage 
 
 Adults in flight 
 
 Swarming termites are a definite sign of 
 infestation. However, a termite flight does 
 not necessarily mean that damage is being 
 done. For example, termites may inhabit 
 an earth-filled porch, feeding on buried 
 wood that was carelessly shoveled in when 
 the original fill was made {see Fig. 2). 
 However, if the porch is properly sealed 
 away from the foundation, the termites 
 may not have access to the wood members 
 of the building. 
 
 Shelter tubes 
 
 An important sign of termite infestation 
 is shelter tubes (Fig. 3, p. 5). Termites 
 build them from particles of sand or earth, 
 or minute bits of wood, or both, coating 
 them with a gluelike substance which they 
 secrete. The particles may adhere so 
 loosely that they form a coarse filigree. 
 In such shelter tubes, light enters freely; 
 
 STUCCO — 
 SHEATHING- 
 
 1^ SOLE WLOOI 
 
 ^PLATE ^-SUBFL 
 
 TERMITE TUBES 
 OVER SURFACE ANO 
 THROUGH VOIDS 
 IN WALL 
 
 Fig. 2. One of the most common sources of 
 subterranean termite infestation: wood debris 
 in the soil near the foundation. Even if the 
 area is sealed off from the substructure of the 
 dwelling, termites may infiltrate through cracks 
 or voids. 
 
 [4] 
 
Fig. 3, top. Three types of earthen shelter 
 tubes. Left, utility or working tubes; center, 
 exploratory or migratory tubes; right, sus- 
 pended or drop tubes. Fig. 4, below. A termite 
 worker in the process of building an explora- 
 tory or migratory shelter tube. 
 
 contrary to popular belief, termites have 
 no aversion to light. Shelter tubes seem 
 to be constructed mainly for protection 
 against natural enemies. Through them 
 termites communicate between their nests 
 in the moist soil and the wood which is 
 their food source. Tubes attached to foun- 
 dations, walls and other structures can 
 span distances up to 20 to 30 feet, or even 
 more. 
 
 While shelter tubes are usually attached 
 to the inside walls of foundations, occa- 
 sionally they may extend unsupported 
 from the soil to low wood members. 
 Sometimes they stand upright in clusters, 
 usually around floor furnaces. 
 
 Shelter tubes indicate termite damage. 
 Their absence, however, does not insure 
 a termite-free structure. The insects may 
 reach sills or other wood members through 
 cracks or voids in the foundation wall, or 
 from earth-filled porches, steps, stoops, 
 terraces, and patios (Fig. 2, p. 4; Fig. 5, 
 p. 6). Of those termite-infested California 
 buildings with no wood contact with the 
 ground, more than half of the infestations 
 originate in these earth-filled extensions 
 of the main building. 
 
 [5] 
 
Utility or working tubes form the run- 
 ways through which termites feeding in 
 the wood above the foundations can peri- 
 odically return to the moist atmosphere 
 in their subterranean galleries in order 
 to replenish body moisture lost while feed- 
 ing above ground. These tubes are wide, 
 
 flattened, and usually extend from the 
 soil to the wood above. If these tubes are 
 broken as rapidly as they are repaired, 
 and the termites have no other sheltered 
 passage through which to return to their 
 nests below the ground, and no other 
 source of moisture, they will eventually 
 
 1. CRACKS IN FOUNDATION PERMIT HIDDEN POINTS OF 
 ENTRY FROM SOIL TO SILL. 
 
 2. POSTS THROUGH CONCRETE IN CONTACT WITH SUB- 
 STRUCTURAL SOIL. WATCH DOOR FRAMES AND INTERMEDI- 
 ATE SUPPORTING POSTS. 
 
 3. WOOD FRAMING MEMBERS IN CONTACT WITH EARTHFILL 
 UNDER CONCRETE SLAB. 
 
 4. FORM BOARDS LEFT IN PLACE CONTRIBUTE TO TERMITE 
 FOOD SUPPLY. 
 
 5. LEAKING PIPES AND DRIPPING FAUCETS SUSTAIN SOIL 
 MOISTURE. EXCESS IRRIGATION HAS SAME EFFECT. 
 
 6. SHRUBBERY BLOCKING AIR FLOW THROUGH VENTS. 
 
 7. DEBRIS SUPPORTS TERMITE COLONY UNTIL LARGE POPU- 
 LATION ATTACKS SUPERSTRUCTURE. 
 
 8. HEATING UNIT ACCELERATES TE-RMITE DEVELOPMENT BY 
 MAINTAINING WARMTH OF COLONY ON A YEAR-ROUND 
 BASIS. 
 
 9. FOUNDATION WALL TOO LOW PERMITS WOOD TO CON- 
 TACT SOIL. ADDING TOP SOIL OFTEN BUILDS EXTERIOR 
 GRADE UP TO SILL LEVEL. 
 
 10. FOOTING TOO LOW OR SOIL THROWN AGAINST IT 
 CAUSES WOOD-SOIL CONTACT. THERE SHOULD BE 8 INCHES 
 OF CLEAN CONCRETE BETWEEN SOIL AND PIER BLOCK. 
 
 11. STUCCO CARRIED DOWN OVER CONCRETE FOUNDA- 
 TION PERMITS HIDDEN ENTRANCE BETWEEN STUCCO AND 
 FOUNDATION IF BOND FAILS. 
 
 12. INSUFFICIENT CLEARANCE FOR INSPECTION ALSO PER- 
 MITS EASY CONSTRUCTION OF TERMITE SHELTER TUBES 
 FROM SOIL TO WOOD. 
 
 13. WOOD FRAMING OF CRAWL HOLE FORMING WOOD- 
 SOIL CONTACT. 
 
 14. MUD SILL AND OR POSTS IN CONTACT WITH SOIL. 
 
 15. WOOD SIDING AND SKIRTING FORM SOIL CONTACT. 
 SHOULD BE A MINIMUM OF 3 INCHES CLEARANCE BETWEEN 
 SKIRTING AND SOIL. 
 
 16. PORCH STEPS IN CONTACT WITH SOIL. ALSO WATCH 
 FOR LADDERS AND OTHER WOODEN APPURTENANCES. 
 
 17. DOWNSPOUTS SHOULD CARRY WATER AWAY FROM 
 BUILDING. 
 
 18. IMPROPER MAINTENANCE OF SOIL PILED AGAINST PIER 
 FOOTING. ALSO MAKES CAREFUL INSPECTION IMPOSSIBLE. 
 
 19. WOOD GIRDER ENTERING RECESS AND FOUNDATION 
 WALL. SHOULD HAVE 1 INCH FREE AIR SPACE ON BOTH 
 SIDES AND END AND BE PROTECTED WITH A MOISTURE IM- 
 PERVIOUS SEAL. 
 
 20. VENTS PLACED BETWEEN JOISTS TUNNEL AIR THROUGH 
 SPACE WITHOUT PROVIDING GOOD SUBSTRUCTURAL AERA- 
 TION. VENTS PLACED IN FOUNDATION WALL GIVE BETTER 
 AIR CIRCULATION. 
 
 Fig. 5. Twenty points of faulty home construction and maintenance that may lead to infesta- 
 tion by subterranean termites. Illustration by courtesy of the Eleventh Naval District, San 
 Diego. 
 
 [6] 
 
perish. However, the termites below the 
 broken tube will continue to form new 
 tubes or concentrate their attack else- 
 where. 
 
 Exploratory or migratory tubes look 
 similar to working tubes, but are built 
 less strongly, usually do not reach the 
 wood above, and have small exit holes. 
 The photograph on page 5 shows a 
 worker termite constructing such a tube. 
 Suspended or drop tubes are working 
 tubes built downward from the wood 
 member to the soil. They are lighter in 
 color because more wood fiber is used in 
 their construction. 
 
 Swarming tubes are constructed at 
 swarming time as exits for the winged 
 reproductive forms. This type of tube 
 usually extends from the ground for only 
 about 4 to 8 inches but under particularly 
 favorable circumstances may extend sev- 
 eral feet and may even reach wood mem- 
 bers of the substructure. Swarming tubes 
 are often found around floor furnaces or 
 other warm places. 
 
 Blisters, darkened areas, moisture 
 
 Blisters or darkened areas in the flooring 
 sometimes indicate the presence of ter- 
 mites. Moisture caused by condensation 
 or leakage invites termite attack or dry 
 rot. This is particularly true in subframing 
 adjacent to first-floor showers, bathrooms, 
 
 toilets, sinks, laundry facilities, and other 
 plumbed areas visible from the area under 
 the building. Therefore moist areas should 
 be examined with particular care and the 
 source of the moisture should be elimi- 
 nated. 
 
 Probing suspected areas 
 Piercing the wood. If you suspect ter- 
 mite infestation, you will do well to probe 
 suspected areas around shelter tubes, 
 around holes or cracks in the wood 
 plugged with a mixture of earth and 
 partly digested wood that the termites use 
 for this purpose, and around blisters, 
 darkened areas, and moist spots. The ter- 
 mites feed to within a short distance of 
 the surface and may have eaten a piece 
 of wood entirely hollow before their 
 presence is suspected. You can easily 
 pierce infested areas with a sharp instru- 
 ment such as an ice pick or a screwdriver, 
 often just with the pressure of a finger. 
 Water testing showers is a common pro- 
 cedure in termite inspection and control. 
 Plug the drain and let both cold and hot 
 water run until it covers the shower floor 
 to a depth of one inch. The shower pan is 
 considered satisfactory if the area below 
 the shower floor shows no moisture after 
 15 minutes. If you find a leak, repair or 
 replace the subdrain and shower pan; in 
 severe cases of termite damage or dry rot, 
 some timbers may require replacing. 
 
 Periodic General Inspections 
 
 Some homeowners periodically inspect 
 their entire premises for termite activity. 
 Ordinarily, however, it is advisable to call 
 on a reputable, licensed termite operator 
 for inspection, cost estimate of control 
 and, if necessary, repair or replacement 
 of damaged areas. Some termite operators 
 offer free inspection, others charge an in- 
 spection fee if no further work is done 
 on the inspected premises. It is worth the 
 nominal fee to be free of anxiety, in case 
 no signs of current termite activity are 
 found. The homeowner may arrange for 
 a periodic inspection service done by ex- 
 
 perienced personnel, usually once a year. 
 Locating the termite colonies and de- 
 termining the best way to combat the 
 insects is very difficult and strenuous 
 work. The inspector must crawl on his 
 stomach over dust, mud, and debris, often 
 in spaces barely high enough to admit his 
 body. He must crawl the entire distance 
 around the inside of the foundation, in- 
 specting and probing the wood structures, 
 in addition to inspecting areas under 
 showers, sinks, and in the vicinity of 
 floor furnaces. In southern California a 
 complete inspection includes the exami- 
 
 [7] 
 
Fig. 6. Cross sections of Douglas fir lumber showing characteristic patterns of the galleries 
 of the subterranean termites (above) and the galleries and chambers of the drywood termites 
 (below). 
 
 nation of the attic for drywood termites. 
 The narrowly confined spaces of flat- 
 roofed houses, the high attic temperatures, 
 the dust, and the prolonged crawling over 
 rafters make a thorough inspection an 
 ordeal. Termite inspection also requires 
 much experience and knowledge about 
 the habits of termites. A correct diagnosis 
 is essential for successful treatment. 
 
 A reliable operator can provide you 
 with a plan of the inspected premises, in- 
 dicating the points of infestation and haz- 
 ardous conditions, and an estimate of con- 
 trol and repair cost. All termite operators, 
 in accordance with state law, must file a 
 standard inspection report form with the 
 Structural Pest Control Board. Thus the 
 means exist of checking the report forms 
 of various termite operators and exposing 
 those who are addicted to substandard or 
 
 fraudulent practices. Such operators may 
 then lose their pest control licenses. 
 
 It takes a long time for termites to 
 cause appreciable additional damage. No 
 reliable operator will attempt to impress 
 you with the urgency of immediate action. 
 You will have ample time to investigate 
 the reliability of the operator and to com- 
 pare his diagnosis and estimate of cost 
 with that of other termite operators. How- 
 ever, the lowest bidder is not necessarily 
 the most reliable operator. If his work is 
 not thorough and is not based on well- 
 established basic principles of termite 
 control, his job may in the long run prove 
 to be the more expensive. Furthermore, 
 some operators may bid low, but will find 
 additional work to do after beginning the 
 job, eventually exceeding the estimates of 
 competitive bidders. 
 
 Preventive and Control Measures 
 
 In successful termite control, the 
 "ounce of prevention" may save hours of 
 costly cure in labor and repairs. Avoiding 
 
 conditions that favor establishment of 
 subterranean termites will decrease the 
 chances for termite damage. 
 
 [8] 
 
Moisture 
 
 Termite activity is favored by moist sur- 
 face soil. Even if the surface beneath a 
 building is dry, however, termites can 
 still exist by extending their galleries down 
 to the moist soil below. The following 
 precautions will help to minimize termite 
 infestation : 
 
 Use every practicable site-grading and 
 construction measure to prevent accumu- 
 lation of moisture around and under 
 buildings. 
 
 Where it is not possible to have com- 
 pletely dry soil under a building, install 
 ventilation to remove moist air from the 
 substructure area. 
 
 Do dot allow shrubbery to obstruct the 
 vents. (Fig. 5, p. 6.) 
 
 Avoid prolonged sprinkling against the 
 sides of stucco buildings as much as pos- 
 sible, for the resulting dampness may 
 cause the stucco to part from the founda- 
 tion wall, allowing access for termites. 
 Leaking faucets may have the same effect. 
 (Fig. 5, p. 6.) 
 
 Clean the concrete surface of your 
 foundation and dash it with a rich cement 
 mixture before applying the stucco; it 
 will make the stucco adhere more firmly 
 to the foundation, reducing the chances 
 for termite infiltration. 
 
 Debris 
 
 Termites can become established only 
 when there is adequate food on or under 
 the ground to sustain them. Here are a 
 few ways to eliminate their food supply: 
 
 Remove buried stumps, logs, and roots 
 from your building site. 
 
 Remove scraps of lumber from the 
 crawl space under the building after con- 
 struction is completed. (Fig. 5, p. 6.) 
 
 Do not include wood scraps with the 
 earth to fill porches, steps, stoops, ter- 
 races, and patios — the most frequent in- 
 itial sites of termite infestation. (Fig. 2, 
 p. 4.) 
 
 Completely remove foundation forms 
 and grade stakes. (Fig. 5, p. 6.) If parts 
 of forms and broken stakes have been left 
 in the ground and cannot be removed 
 easily, soak these remaining portions with 
 an oil-borne wood preservative. 
 
 Home construction 
 
 No structural design, either in conven- 
 tional or slab-on-ground construction, has 
 yet been developed that is absolutely proof 
 against termite infestation, but proper de- 
 sign greatly decreases the incidence of 
 damage. The following suggestions will 
 help: 
 
 Be sure that no wood member of the 
 structure makes contact with the ground. 
 Install solid concrete foundations or piers; 
 they are least susceptible to termite pene- 
 tration although the insects may gain ac- 
 cess through cracks that develop later. 
 (Fig. 2, p. 4; Fig. 5, p. 6.) 
 
 Follow the specifications of the Cali- 
 fornia Building Code, particularly those 
 on installation of termite shields, mini- 
 mum clearance between members of the 
 substructure and grade level, and ven- 
 tilation. 
 
 The same rules for foundation clear- 
 ance and ventilation should also apply to 
 wood frame porches and steps. Do not 
 allow wood to come in contact with the 
 ground anywhere. (Fig. 5, p. 6.) 
 
 In combatting termites, it is of little 
 avail to follow Code specifications if you 
 pile earth against the foundations. 
 
 Keep planting boxes built on the 
 ground separated from the main structure 
 by at least 4 inches; if possible, keep them 
 below the level of the first wood in con- 
 tact with the foundation wall. 
 
 Chemical treatment of lumber 
 
 What to treat. Lumber adequately treated 
 with an approved preservative resists at- 
 tack by termites and fungi. It is usually 
 too expensive to treat all lumber, even in 
 the substructure. In this event, use treated 
 lumber only where it is most subject to at- 
 tack by termites or decay. Most of this 
 lumber is structurally vital and difficult to 
 replace; thus the extra cost for treatment 
 is well justified. Treated lumber offers the 
 additional advantage of forcing the ter- 
 mites to tube around it and thus expose 
 their activities to plain view, making it 
 possible to detect and control them. 
 
 Use of treated lumber 
 
 Normally it would be wise to use treated 
 lumber for the following structures: 
 
 [9] 
 
For conventional construction — sills, 
 headers, pier posts. 
 
 For slab-on-ground construction — 
 sleepers, all structural framing lumber 
 contacting the slab. 
 
 All wood structures less than 12 inches 
 from the ground which might be used in 
 the construction of porches, steps, breeze- 
 ways, terraces, and patios. 
 
 All wood door frames and window 
 frames of access openings to crawl spaces 
 in contact with masonry, as well as wood 
 gutters. 
 
 Dip or thoroughly brush the cut ends 
 of all treated lumber with an acceptable 
 material used for wood preservation. 
 Treated lumber should carry the brand, 
 the name of the treater, preservative used, 
 retention of preservative in pounds per 
 cubic foot, and the maximum moisture 
 content of the wood. A certificate may 
 be obtained providing this information, 
 or stating compliance with the recom- 
 mended specification or standards. Ac- 
 ceptable standards are the Federal Speci- 
 fications TT-W-5 71 (current edition) and 
 the Standards of the American Wood Pre- 
 servers' Association. 
 
 Durable woods. In place of wood treated 
 with a preservative, certain naturally dur- 
 able woods may be used, including the 
 Foundation Grade redwood, cedar, or "all 
 heartwood" cypress, in accordance with 
 the grading rules of the appropriate na- 
 tionally recognized lumber association. 
 Cost of total treatment. Some home 
 owners have used treated lumber for all 
 the rough framing of the house. The 
 treated lumber, plus the chemical solution 
 required for dipping or painting the cut 
 ends, adds about 3 per cent to the cost 
 of a new home. The treated members are 
 protected not only against subterranean 
 termites, but also against drywood ter- 
 mites, beetles, and dry rot. A less expen- 
 sive procedure, which still offers a high 
 degree of protection, would be the treat- 
 ment of all wood up to and including the 
 subfloor. This will cost about 10 cents a 
 square foot. 
 
 Soil treatment before construction 
 
 Most people think of soil treatment for 
 termite control primarily as a control 
 
 measure after the structure has been built; 
 but soil treatment can also be used before 
 construction of the house, as a deterrent 
 to termite attack. The experience of the 
 United States Forest Service and others 
 has shown that soil treated with certain 
 insecticides may be expected to form an 
 effective barrier against termites for 15 
 years or more. 
 
 Extensive long-term field tests by the 
 Department of Entomology on the Los 
 Angeles campus are expected to yield re- 
 liable information on relative effectiveness 
 of eight different insecticides against the 
 western subterranean termite. Meanwhile, 
 it is suggested that insecticides recom- 
 mended in the National Pest Control As- 
 sociation's 1963 revision of "Chemicals 
 in Subterranean Termite Control," and 
 endorsed by the United States Forest 
 Service, be used at the concentrations 
 suggested. 
 
 Recommended materials are: aldrin at 
 0.5 per cent; chlordane at 1 per cent; 
 dieldren at 0.5 per cent; heptachlor at 0.5 
 per cent, or lindane at 0.8 per cent. These 
 insecticides may be used either as water 
 emulsions or in solution in an oil not 
 heavier than No. 2 fuel oil. However, do 
 not use oil solutions under concrete slabs, 
 for they may penetrate to the surface of 
 the slab, causing unsightly stains. 
 
 These insecticides are bought in the 
 form of emulsifiable concentrates which 
 differ in the per cent of toxicant each con- 
 tains. The concentrated form must be di- 
 luted with the correct volume of water 
 to obtain a solution for application which 
 contains the recommended amount of 
 toxicant for termite control. Emulsifiable 
 concentrates emulsify readily in water. 
 The globules of insecticide, when applied, 
 are largely sieved out by the first inch of 
 soil through which they pass. This forms 
 an adequate barrier against termites. 
 
 On the other hand, when the emulsi- 
 fiable concentrate is used in a fuel oil 
 carrier, the insecticide stays in solution 
 regardless of how deep the solution pene- 
 trates. Therefore, fuel oil solutions are 
 useful when it is desirable for the insecti- 
 cide to penetrate to a great depth in a 
 limited area, for instance, around a grade 
 stake which cannot be removed. A lim- 
 ited degree of wood penetration, particu- 
 
 [10] 
 
CAUTION 
 
 All insecticides used for the preven- 
 tion and control of subterranean 
 termites are toxic to man. Labels 
 on containers that relate to the safe 
 use of the contents should be care- 
 fully read and heeded. Insecticides 
 should always be kept in their orig- 
 inal, properly labeled containers 
 and stored where children and pets 
 can not get at them. Excess spray 
 material and empty containers 
 should be disposed of so that they 
 do not present a hazard to man, 
 pets or wildlife. Protective equip- 
 ment, such as chemical-resistant 
 gloves, goggles, and respirators 
 should be used. Poisons may be ab- 
 sorbed through the skin. Contami- 
 nated parts of the body should be 
 washed thoroughly with soap and 
 water. 
 
 Termite operators should bear 
 in mind that the repeated exposure 
 to insecticides resulting from the 
 daily use of these compounds can 
 cause a cumulative or chronic poi- 
 soning which may become seri- 
 ous without preliminary warning 
 and which may be difficult to diag- 
 nose. Therefore it is particularly 
 important that operators observe 
 the rules of safety with greatest 
 diligence. 
 
 larly in the direction of the grain, is also 
 possible with fuel oil solutions. 
 
 There are certain patented materials 
 on the market which do not specify the 
 compounds they contain. They may be 
 effective if they contain one or more of 
 the recommended materials. They may be 
 used if approved by the U. S. Forest Serv- 
 ice, and also show proof that they will 
 have no toxic effects on man or desirable 
 plant life when used as recommended. 
 
 Rates of application 
 Slab on ground. Apply one gallon per 
 10 square feet as an overall treatment 
 under the slab, and under attached 
 porches, using a sprayer at low pressure, 
 or even a sprinkling can. Apply W2 gal- 
 lons per 10 square feet as an overall treat- 
 ment applied to washed and ungraded 
 gravel fills, or fills of an absorbent material 
 such as cinders. 
 
 Application should be heaviest around 
 utility pipes. Although the concrete ini- 
 tially adheres to the pipes, it later breaks 
 away because the two materials contract 
 or expand with changes in temperature. 
 Termites can then crawl through any re- 
 sulting cracks. 
 
 Apply 2 gallons per 5 linear feet along 
 the outside of the foundation in a trench 
 dug for this purpose. 
 Conventional construction. A good time 
 to insure against termite infestation in 
 conventional house construction is when 
 the foundations are up, but before con- 
 struction of the house has started. For 
 these applications the following rates are 
 recommended: 
 
 Apply 2 gallons per 5 linear feet to 
 critical areas under the house, such as 
 along the inside of foundation walls, 
 around interior partition foundation walls, 
 and around piers and utility entrances. Do 
 not make an overall treatment in such 
 areas. 
 
 Along the outside of foundation walls, 
 including the parts to which entrance 
 platforms, porches, etc., are attached, ap- 
 ply 2 gallons per 5 linear feet where the 
 foundation is shallow, and 4 gallons per 
 5 linear feet where the foundation is deep. 
 Trenches should be dug for this purpose. 
 
 Apply 1 gallon per 10 square feet of soil 
 surface as an overall treatment only where 
 attached porches, entrance platforms, 
 utility entrances, etc., have covering slabs 
 on fill on ground. 
 
 Voids. Treat all voids of unit masonry 
 walls and piers with 1 gallon of dilute 
 insecticide emulsion or solution to 5 
 linear feet, applied from the surface of 
 the ground to the footing. Extensive drill- 
 ing may be required to reach these voids. 
 
 [in 
 
Depth of Penetration 
 
 Insecticide emulsions applied at the rate 
 of 1 gallon to 10 square feet penetrate the 
 average soil to a distance of only about 
 1 inch. Even when applied at a much 
 higher dosage, the liquid does not pene- 
 trate deeply enough to reach average ter- 
 mite galleries. Besides, the globules of 
 insecticide are strained out by soil par- 
 ticles and the greater part of the insecti- 
 cide remains in the upper V2 inch of soil. 
 Even with oil or water solutions the con- 
 centration of insecticide is much lower 
 below the first Vi inch of soil. For these 
 reasons, the general soil treatment as de- 
 scribed here will only prevent termites 
 from penetrating the treated ground, but 
 will not destroy existing colonies. How- 
 ever, you may be able to reach some ter- 
 mite colonies, such as those in buried 
 wood (Fig. 2, p. 4) by the use of high 
 volumes applied to limited areas. Trench- 
 ing is the preferred method of application. 
 
 Pretreatment for slabs 
 
 Preconstruction treatment is particularly 
 recommended for slab-on-ground con- 
 struction. Slab-on-ground construction 
 was once considered to be the answer to 
 the termite problem. However, experience 
 has shown that the slab is no effective 
 barrier against termites; they can pene- 
 trate the slab through cracks in the con- 
 crete or in spots where the concrete has 
 receded from around utility pipes. After 
 the termites are established, it is much 
 harder to locate the source of infestation 
 than in conventional construction where 
 crawl space is available. Likewise, control 
 under the slab is more difficult, more ex- 
 pensive, and less likely to be successful 
 than in conventional construction. For 
 these reasons it is particularly advisable 
 to treat the soil before the concrete is 
 poured for slab-on-ground construction. 
 Fortunately, this type of structure lends 
 itself well to preconstruction treatment, 
 for there is no crawl space to contaminate, 
 and most insecticides can be applied safely 
 to the area to be covered with concrete. 
 
 Soil treatment after construction 
 
 Control under slab. Termite control 
 under existing slab is sometimes necessary; 
 it is difficult and expensive. Holes must 
 be drilled either vertically through the 
 slab or horizontally from outside the 
 foundation at a height that will allow the 
 termite operator to force an insecticide 
 liquid beneath the slab and into the soil 
 throughout the infested area. Sometimes 
 liquid fumigants are used. The drilling 
 must be done without breaking utility 
 pipes immediately under the slab or radi- 
 ant heating pipes embedded in the con- 
 crete. Preconstruction treatment of the 
 soil is particularly important where slab- 
 on-ground construction is used; preventive 
 measures are more effective and less ex- 
 pensive in the long run. 
 Control in conventional construction. 
 Conventional construction with its crawl 
 space enables the inspector to locate 
 sources of termite infestation with con- 
 siderable accuracy. He can break up 
 shelter tubes, and treat with insecticides 
 the ground from which the tubes arise. 
 Since the area from which the termites 
 originate is ordinarily localized, time and 
 effort can be concentrated on the treat- 
 ment of a small area. His inspection may 
 also reveal points at which structural re- 
 pair or alteration is necessary. 
 Inside the foundation. Digging deep 
 trenches along the entire inside of the 
 foundation and pouring liquid insecticides 
 into the trench is widely recommended, 
 in order to treat the soil; but this recom- 
 mendation is seldom carried out because 
 it is extremely difficult to do such work in 
 the confined quarters of the usual crawl 
 space. However, the treatment of a limited 
 area in this manner, directed against a 
 known source of infestation, is practicable 
 and effective. 
 
 Outside the foundation. Outside the 
 foundation termites may penetrate the 
 mortar joints between cracks or concrete 
 blocks, or they may enter cracks in the 
 poured concrete foundation. They also 
 may build tubes on the outside face of 
 
 [12] 
 
the foundation wall, or enter between the 
 wall and stucco or other covering that 
 has become loose from the concrete. 
 
 Chemical treatment either outside or 
 inside the foundation may consist of di- 
 lute insecticide emulsion applied at the 
 rate of 2 gallons to 5 linear feet in the 
 soil adjacent to the foundation. Treat- 
 ment may require digging a trench the 
 width of a shovel and at least 30 inches 
 deep. Some of the insecticide should be 
 applied at the bottom of the trench; the 
 remainder at about 6-inch intervals as 
 the soil is replaced. A shallower trench, 
 12 to 15 inches deep, may be dug, and 
 auger or rod holes — about 6 inches apart 
 — may be extended from the bottom of the 
 trench to the footing of the foundation. 
 Half the liquid can be poured into these 
 holes, the rest mixed with the earth as 
 the trench is filled. 
 
 Structural repair work 
 
 Even the most careful attention to termite 
 prevention measures does not guarantee 
 success. The incidence of termites in- 
 creases with the age of the building, until 
 in some areas there is hardly a house in 
 which termite control has not been neces- 
 sary at one time or another. Just as sound 
 structural design is important for termite 
 prevention, so is structural repair work 
 important for termite control. 
 Constant vigilance is needed. Termites 
 often originate in earth-filled porches, 
 steps, stoops, terraces, patios, breezeways, 
 walks, or other slab-covered areas sur- 
 rounding the house. Originally these struc- 
 tures may have been adequately sealed 
 away from the foundation of the main 
 building, but earthquakes or settling of 
 the earth may have caused cracks in the 
 foundation. If the cracks are %2 inch or 
 wider, termites will be able to penetrate 
 the foundation and reach lumber, such as 
 sills, flooring, and studs, which was previ- 
 ously safe. (Fig. 2, p. 4.) Termites may 
 even scrape out passageways with their 
 mandibles in cracks in concrete that were 
 originally too narrow to admit them. 
 "Seal-offfs." The most common structural 
 repair consists of cracking the concrete 
 of porches, patios, terraces, and drive- 
 ways, away from the foundation of the 
 
 main structure, and sealing the infested 
 area away from this foundation by a 4- 
 inch-thick wall of concrete. This type of 
 job is called a seal-off. The termite colony 
 need not be exterminated, for these insects 
 can do no damage if they are denied ac- 
 cess to the wood members of the building. 
 You may still notice their activity, how- 
 ever, when the winged termites begin to 
 emerge from cracks in the slab after the 
 first fall rains. The chances are small that 
 these winged insects may start a new col- 
 ony on your premises if you have taken 
 care of all structural defects that would 
 allow them to reach wood. If, despite the 
 "seal-off" you wish to get rid of termites 
 under the earth-filled extensions of the 
 foundation, they may be exterminated by 
 drilling through the concrete cap and 
 treating as described for slab-on-ground 
 construction. 
 
 Raising foundations. The height of the 
 foundation is sometimes raised to bring 
 the sills at least 6 inches above grade. 
 Usually the substructure is removed, a 
 few linear feet at a time; the new founda- 
 tion is built up to the desired height, and 
 the new substructure is built upon it. 
 Sometimes the termite operator chooses 
 to shore up the entire structure and then 
 raise the entire foundation at once. 
 
 In garage interiors, the sills and studs 
 are ordinarily not covered, as is occa- 
 sionally true in certain other types of 
 buildings. When an uncovered, infested 
 sill rests on a slab floor, the standard con- 
 trol technique is to remove the sill and 
 cut away the lower ends of the studs. 
 Blocks of masonry are then placed under 
 the new sill to elevate it at least 4 inches 
 above the adjacent grade levels. Another 
 procedure is to paint the uncovered sills 
 and the bases of the studs with a penta- 
 chlorophenol emulsion, as is done against 
 the dry wood termite (p. 14). 
 Flash walls. When raising the foundation 
 might be excessively expensive (as when 
 the floor joists rest on the sill) a flash 
 wall is installed instead. This is a solid, 
 poured-concrete facing, firmly bonded to 
 the foundation and extending at least 4 
 inches below the top of the foundation 
 and no less than 3 inches above the natural 
 grade level. It must be at least 3 inches 
 
 [13 
 
thick and the top sloped to provide ade- 
 quate drainage away from the walls of 
 the house. 
 
 A metal flash wall has become available 
 recently. The exterior soil is trenched and 
 chemically treated, a concrete base is 
 poured, the metal form is installed, and 
 stucco is applied over it. This type of 
 flash wall is hollow, providing for venti- 
 lation and for inspection. It is more water- 
 
 repellent than the conventional concrete 
 flash wall and if a little moisture does 
 enter, it is dried up by air circulation or 
 drains away in the gutter at the base. 
 Sometimes concrete gutters are built when 
 the wood sills on the foundation walls lie 
 at or below grade. The ventile flash wall 
 described above is like a covered gutter 
 which cannot be filled with leaves and 
 debris. 
 
 Other Wood-destroying Insects 
 
 Other insects and some fungi attack 
 the woodwork in buildings. It is impor- 
 tant to distinguish their damage from that 
 of the subterranean termite as control 
 measures may differ. 
 
 Drywood termite 
 
 The common drywood termite Incisi- 
 termes minor (Hagen), damages build- 
 ings in southern California about as often 
 as does the subterranean species, but 
 ordinarily causes less serious damage. It 
 may be found as far north as the San 
 Francisco Bay region and even north of 
 Sacramento. The drywood termite looks 
 like the subterranean termite but is larger 
 and its winged form has a reddish head 
 while that of the subterranean is black. 
 Drywood termites can become established 
 anywhere in the house, most likely in 
 attics and window frames; they require no 
 connection with the ground. Their pres- 
 ence is indicated by the emergence of 
 winged termites from the wood, or by 
 small piles of straw-colored to reddish 
 brown fecal pellets, appearing somewhat 
 like coarse sand, which filter down from 
 chinks or "kick-out holes" in the infested 
 wood. 
 
 Control 
 
 For localized and exposed infestations, 
 inject insecticide dusts or a solution of 
 ethylene dibromide into the termite bur- 
 rows, or apply oil-pentachlorophenol 
 solutions to the outer surface of infested 
 timbers, particularly to crevices where 
 wood joins wood. A paste emulsion of 
 such a solution is available which is ap- 
 plied with a paint brush in a thick layer, 
 
 to insure deep penetration of the wood. 
 More widely distributed infestations are 
 controlled by fumigating the entire build- 
 ing with methyl bromide or other suitable 
 gases. 
 
 Following fumigation or other treat- 
 ment, most termite operators are now ap- 
 plying a highly sorptive fluoridated silica 
 aerogel dust (Dri-Die 67) to prevent re- 
 infestation by drywood termites. If the 
 termites crawl about on wood coated with 
 a barely visible film of dust, the dust 
 adheres to their bodies, absorbs the thin 
 layer of wax that protects them from dry- 
 ing out, and the termites die as the result 
 of rapid desiccation. (The dust is a pre- 
 ventive measure which provides only a 
 surface film on the wood. The termites 
 already infesting the wood must first be 
 destroyed by other means.) One pound 
 of dust is recommended per 1,000 square 
 feet of attic space, applied with a blower 
 able to blow the dust uniformly through 
 the entire attic area from the crawl hole 
 from which it is applied. The dust is effec- 
 tive against termites as long as it is present 
 and consequently it does not have to be 
 renewed when applied to enclosed spaces. 
 It is not a complete guarantee against dry- 
 wood termites, however, for they could 
 gain entry through or under shingles, 
 through exposed rafter stubs beneath the 
 eaves, through foundation vents, etc., and 
 bore into wood without first contacting 
 the dust. The results of six years of ex- 
 tensive commercial usage, however, show 
 proof of significant protection from using 
 the dust, fully justifying its relatively 
 small application cost. 
 
 Since the summer of 1963, Dri-Die 67 
 
 [14] 
 
has been blown into wall voids and the 
 voids under built-in cabinets and shelving 
 of various kinds, as well as into attics, 
 during construction of dwellings and other 
 types of buildings. Access holes made in 
 plasterboard or dry wall to blow in 
 measured amounts of dust are plastered 
 over or otherwise covered in the normal 
 construction procedure. This treatment 
 affords protection against drywood ter- 
 mites and carpenter ants, as well as cock- 
 roaches, silverfish, and other crawling 
 insects that seek voids, cracks, crevices, 
 and other protected places during day- 
 light hours. Combined with the precon- 
 struction treatment of the soil against 
 subterranean termites, dusting voids and 
 enclosed spaces as described above should 
 provide significant permanent protection 
 against many structural and household 
 pests. However, specialized equipment is 
 required for the effective application of 
 the dust and it is generally applied by pest 
 control operators. 
 
 Dampwood termite 
 
 The common dampwood termite, Zoo- 
 termopsis angusticollis (Hagen) is the 
 largest termite found in California; the 
 nymphs are Vi inch long, and the soldiers 
 3 A inch long. Dampwood termites occa- 
 sionally damage wood structures in 
 coastal areas. They live primarily in de- 
 caying wood, but may extend their at- 
 tacks upward into sound wood if sufficient 
 moisture is available. Dampwood termites 
 are destructive only where moisture is 
 abundant, and greatest damage is done in 
 shaded areas. 
 
 Control: Use the same construction and 
 treating methods as recommended for 
 subterranean termites. 
 
 Carpenter ants 
 
 Carpenter ants, like termites, are social 
 insects. They are most apt to invade houses 
 near wooded areas, stump land, or brush- 
 covered vacant lots, but they occasionally 
 infest houses in the larger towns and cities. 
 During swarming periods you may see 
 the winged reproductive forms. Also, the 
 workers may be seen crawling about in 
 the room. Although they construct nests 
 in timber, carpenter ants do not feed on 
 wood. Sometimes you may notice the 
 
 fibrous "sawdust" expelled through slits in 
 the wood by the worker ants. 
 Control: Inject chlordane dust into the 
 burrows. The dust may be blown either 
 into crevices through which ants emerge 
 or into holes drilled into infested wood to 
 reach the galleries. Carpenter ants have 
 also been controlled merely by spraying 
 or dusting the baseboards in the house 
 and the ant runways on the outside of the 
 house with chlordane. 
 
 Powder post beetles 
 
 You may occasionally see small, round 
 exit holes, about the size of pinheads, par- 
 ticularly in hardwood flooring, panelling, 
 and furniture. These holes are made by 
 adult powder post beetles. After the 
 beetles emerge, a fine powder may sift 
 through, much finer than the pellets of 
 drywod termites. 
 
 Control: Spray or paint the infested areas 
 with a solution of ethylene dibromide or 
 a mixture of orthodichlorobenzine, car- 
 bon tetrachloride and pentachlorophenol. 
 Fumigate the entire building when there 
 is danger of damage to the floor finish, or 
 when the infestation is widely distributed. 
 
 Wood wasps 
 
 Damage from wood wasps, also called 
 horntails, has been steadily increasing in 
 recent years. These are large wasplike in- 
 sects, usually an inch or more in length, 
 black or metallic dark blue or with com- 
 binations of black, red and yellow. While 
 they superficially resemble wasps, the 
 head, thorax, and abdomen are uniform 
 in width and closely joined together, while 
 in true wasps the abdomen is joined to 
 the thorax by means of a narrow pedicel 
 or "waist." Wood wasps do not bite or 
 sting. The species most commonly found 
 infesting houses is the metallic dark blue 
 Sirex longicauda Middlekauff. 
 
 Wood wasps tend to attack fire-killed 
 and damaged timber, which is salvageable 
 for certain construction uses. Because of 
 its relatively low value, the lumber is not 
 kiln-dried, a process which would nor- 
 mally kill all insects in it. In residential 
 construction such lumber is sometimes 
 used for studs, joists and subflooring, and 
 this is where insect damage to homes 
 originates. 
 
 [15] 
 
Damage appears in the form of cylin- 
 drical holes, about Va inch in diameter, 
 which occur not in the lumber originally 
 infested but in whatever material the adult 
 wasp must penetrate in its attempt to leave 
 the infested area and fly away. Therefore 
 these holes may be found in walls, includ- 
 ing plaster, and in hardwood floors, car- 
 peting and linoleum. 
 
 Holes in hardwood flooring similar in 
 size to those described above may be 
 made by emerging adult beetles of the 
 new-house borer {Arhopalus product us 
 Leconte) or the black polycaon (Polycaon 
 stouti Leconte). As in the case of wood 
 wasps the larvae live only in softwood of 
 the subfloor and as adults burrow through 
 hardwood in order to escape. 
 
 Whatever damage is done by wood 
 wasps or new-house borers during the first 
 two or three years will be the last, for they 
 will not reinfest the building. Fumigation 
 at the dosages that have been used against 
 this insect has not controlled them. 
 
 Fungi 
 
 Wood may be attacked by dry-rot fungi, 
 mainly Poria incrassata. The damaged 
 wood surface may be checked but con- 
 tains no burrows or cavities; in advanced 
 infestations it has a brownish discolora- 
 tion and crumbles into square or rectangu- 
 lar pieces. The fungi need a moist environ- 
 ment. Dry rot can be avoided by proper 
 drainage or ventilation. In California it is 
 nearly always associated with plumbing 
 leaks, moisture condensing on wood, or 
 wood substructure contact with moist 
 earth. 
 
 Control: Replace damaged wood and 
 eliminate conditions which favor dry rot 
 fungus. In general, proper construction 
 and moisture control practices, which 
 decrease likelihood of subterranean ter- 
 mite infestation, also tend to prevent dry 
 rot. Wood treated with preservatives for 
 subterranean termite control also resists 
 dry-rot fungi. Apply a pentachlorophenol 
 solution or emulsion on untreated wood, 
 particularly at joints. 
 
 In order that the information in our publications may be more intelligible it is sometimes neces- 
 sary to use trade names of products or equipment rather than complicated descriptive or chemical 
 identifications. In so doing it is unavoidable in some cases that similar products which are on the 
 market under other trade names may not be cited. No endorsement of named products is in- 
 tended, nor is criticism implied of similar products which are not mentioned. 
 
 40m-5,'65(F1925)L.P. 
 
 [16]