oJ of 5" or EXCHANGE 9 NfH Miscellaneous Publications, No. 37. MINISTRY OF AGRICULTURE AND , - FISHERIES, BENEFICIAL INSECTS. *'* .% i "'",*"** s" i s * LONDON : PRINTED UNDER THE AUTHORITY OF HIS MAJESTY'S STATIONERY OFFICE. And to be obtained at the Office of the MINISTRY OF AGRICULTURE AND FISHERIES, 10, WHITEHALL PLACE, LONDON, S.W.I. Advertisement Agents: C. Vernon & Sons, Ltd., 38, Holborn Viaduct, B.C. /. 1922. Price 4d Net, Post Free. The Reproduction of Illus- trations for all SCIEN- TIFIC WORK demands accuracy of Colour, Detail and skilled Craftsmanship. The two Four-Colour Plates in this issue, illustrating Lady Birds, Ichneumon Flies and Tachinid Flies (Plate I) '&id Hover relies and Lace- wing FHes e {;PlatG JI) we re -.Engraved and Printed for " the Ministry of Agriculture by : THE SUN ENGRAVING Co., LTD., MILFORD HOUSE, MILFORD LANE, STRAND, LONDON, W.C.2. Telephone: 117 Gerrard (2 lines). Telegraph : " Operameter, Estrand, London? COLOUR WORKS: WATFORD. Specimens of work and quotations will be sent with pleasure. Established 1852. Makers of High Grade Specimen Cabinets for Museums, with interchangeable drawers. Apparatus for collecting and mounting all Natural History Specimens. Large Stock of Scientific Books on Natural History, and publishers of many important Works on Entomology, &c. Cox, H., Handbook of Britis' Coleoptera, 2 vols. Catalogue of British Coleoptera, for Reference and Labelling. Waterhouse, Aid to the Identification of Insects (Exotic), 2 vols. 189 hand-colored plates of rare and striking forms hitherto uiifigured. Butler, Lepidoptera Exotica, 4to. 63 colored plates. Fine useful work. Reitter, Fauna German ica Coleoptera, the best book for naming British and European Coleoptera, 5 vols. 168 colored plates. Solomon Is. and Neio Guinea Lr.pidoptcra line Ornithoptera, Papilios, Delias and 500 species of named Moths, including rare Miliornas, further particulars on application. Largest stock of EXOTIC COLEOPTERA from al! parts of the World, many grand rare species. Also unnamed series from all families at low prices. Catalogue of Apparatus on Application 44, GREAT RUSSELL STREET, LONDON, W.C.I. Fine series of Birdskins from Costa Rica, Philippine, Is., &c. WATKINS & DONCASTER, 36, Strand, London, W.C.2. (Phone. 9451 GERHARD). STOCK EVERYTHING REQUIRED by Collectors and Students of Insects, Plants, Birds' Eggs, &c. LARGE STOCKS on hand of Specimens, also Apparatus and BOOKS on all branches of Natural History, PRICED CATALOGUES FREE. X 16948 WHELDON AND WESLEY, Ltd., BOOKSELLERS, 38, GREAT QUEEN STREET, KINGSWAY, W.C.2. AND 28, ESSEX STREET, STRAND, LONDON, W.C.2. Supply New and Second-hand Books on FARMING, GARDENING, CULTURE OF PLANTS, Books on ANIMALS, BIRDS, INSECTS. Will send post free, on application, their Botanical Catalogue, Part I, 1921. Collection of Works on AGRICULTURE, HUSBANDRY, GARDENING, and ECONOMIC BOTANY, which gives the Titles and Prices of over 3,000 different Books on these Subjects. Price twopence. WHELDON and WESLEY, Ltd., also buy Libraries and Collections of Books on these Subjects. JUST PUBLISHED, SANDERS' LIST OF HYBRID ORCHIDS, with Addenda up to September 1921, One Volume, quarto, 225 pages, interleaved, half roan, 2 5s, net. G. A. BENTALL, 392, STRAND, LONDON, W.C.2. ENTOMOLOGICAL SUPPLIES OF ALL KINDS. Any of the following Price Lists sent without charge: Lists of Apparatus, Books, Palsearctic, I ndo- Australian, African or American Lepidoptenv, also other Insect orders. INSECTS OF ECONOMIC IMPORTANCE A SPECIALITY. PRICE-LIST FOR SAME ON REQUEST. Miscellaneous Publications, No. 37. MINISTRY OF AGRICULTURE AND FISHERIES. BENEFICIAL INSECTS LONDON : PRINTED UNDER THE AUTHORITY OF HIS MAJESTY'S STATIONERY OFFICE. And to be obtained at the Office of the MINISTRY OF AGRICULTURE AND FISHERIES, 10, WHITEHALL PLACE, LONDON, S.W.I. Advertisement Agents: C. Vernon & Sons, Ltd., 38, Holbor.i Viaduct, B.C. I. 1922. Price Id. Net, Post Free. LIST OF CONTENTS. PAGE. Introductory - - 3 Ladybirds - 3 Plate I. - (facing) 4 Ichneumon Flies 5 Tachinid Flies - 7 Hover Flies 7 Lacewing Flies - - 8 Plate II. (f^ing) 8 Artificial encouragement of Beneficial Insects - - - 9 Technical Description of Plates - 11 BENEFICIAL INSECTS. $r*,ry INTRODUCTORY. In their relation to cultivated crops, insects may conveniently be divided into three groups, viz. : Pests those which are harmful, causing by their depredations serious loss to the cultivator and a diminution of the country's food supply; Neutral or negligible those which do not directly influence crop production ; Beneficial those which by predaceous or parasitic habits diminish and keep in check the numbers of the Pests. There is some overlapping between these three groups, but it is generally possible to assign an insect to one or the other. In considering beneficial insects from the cultivator's point of view, it is only possible to deal with certain large groups, various members of which attack and destroy the worst insect pests to agriculture and horticulture. Of these groups, five are outstanding as amongst the very best friends possessed by the farmer, gardener and fruit-grower : they are Ladybirds, Lacewing Flies, Hover Flies, Ichneumon Flies, and Tachinid Flies. Only*' too frequently these insects are mistaken for foes and destroyed. It is hoped that the brief descriptions of them and short outlines of their life-histories herein given may help towards their wider recognition. In connection with all of them one point must first be emphasised : Beneficial insects seldom, if ever, exterminate a pest, or extermination of themselves would be likely to follow. The most they do is so to check the pests (which would other- wise breed in colossal numbers) that the damage suffered by crops is reduced to an almost negligible amount. Their work of destruction goes on unobtrusively, and only fails when some influence favours the pest or acts adversely on the parasite, allowing the former to survive in such overwhelming numbers that an effective control no longer obtains. The cultivator himself must then resort to artificial measures of pest destruc- tion, but in doing so he must remember that he is often killing both friend and foe alike. He must, therefore, having once begun, be prepared to continue his spraying or other measures, and himself carry out the work previously left to Nature. LADYBIRDS. Ladybirds are beetles which do untold good by feeding in the adult and grub (larval) stages upon Aphides (Greenfly or " Blight "). Some kinds also feed on Scale Insects, Suckers, or other pests. r (5)16948 Wt P 2120 R 7 10,000 4/22 M160927 The adult Ladybird is well known and is usually respected by everybody; but in the grub stage, being so very different in appearance and somewhat repulsive to look at, it is by no means so often recognised and frequently falls a prey to the uninformed zeal of the gardener, who complains of Greenfly while he busily destroys perhaps its greatest enemy the Lady- bird grub. The appetite of these grubs is enormous and they appear to feed almost continuously, 30 to 40 Aphides being devoured with scarcely a pause. Description and Life History. The Eggs (Plate L, Fig. 2) of the Ladybird are conical in shape and yellow in colour, going brown when about to hatch. They are placed by the adult insect in small groups upon the stem or underside of the leaves of a plant infested by Aphides. The Grub (Plate I., Fig. 3) is a flattish, black, ugly creature with a big head and six legs on the fore part of the body. In some species it is marked with yellowish or reddish and white markings. After hatching from the egg, it soon begins to hunt, and on arriving at the first group of Aphides eats its way steadily through them. It is very active, an indefatigable hunter, and, on having killed out the prey on a particular plant or branch, will pass rapidly to the next. It grows quickly, changes its skin several times, and on becoming full-fed turns to a pupa on the plant or anything adjoining. The Pupa (Plate I., Fig. 4) is a pomewhat dried-up looking object when first formed, light yellow, but afterwards darker in colour. The shrivelled skin of the grub, out of which the pupa has emerged, remains wrapped round the " tail." After a few days, varying with the season, this pupa splits and the adult Ladybird crawls forth, being at first soft and pale, but hardening in a few hours and attaining the characteristic coloration. The Perfect Insect (Plate L, Fig. 1). The little round, red beetles with black spots, known as Ladybirds, are familiar to everyone. There are, however, many kinds, some red or yellow with black spots, others black with red spots. In certain kinds even the separate individuals vary in colour from black to red according to which colour predominates. Nearly all, however, have the characteristic shape and appearance, so that, apart from colour, they may easily be recognised as undoubted Ladybirds. On emergence from the pupa, Ladybirds soon begin to feed upon Aphides. The females, after pairing, lay eggs and the life-cycle begins again. There are several broods throughout the summer, the last one hybernating. spending the winter asleep under bark of trees or in some cranny, when at times considerable numbers collect together in one place. With the warmth of spring they emerge from their hiding places and the first eggs of the season are laid. ICHNEUMON FLIES.* Under this popular designation may be included several thousand allied species of insects, examples of which are shown on Plate I., Figs. 6, 7, 8 and 9. They are not flies in the zoological sense, but are all close relations of the bees and wasps, albeit not necessarily like them in appearance. They range in size from extremely minute insects, hardly visible to the naked eye, up to as long or even longer than the Hornet, though less heavily built. They have jaws, long antennae, and four wings, which are always carried along the back and are small in propor- tion to the creature with few ribs in the supporting framework. In habit they are very active and energetic. Ichneumons probably comprise (with the possible exception of adverse weather condi- tions) the most potent of all the forces operating to keep in check an overwhelming increase in other insects a misfortune which always threatens. They do not achieve this by devouring them outright as the Ladybird does, but are parasitic and lay their eggs in or upon the insects they attack. The Ichneumon grubs then feed upon the juices of their victims and come to maturity in their stead. Practically all the other orders of insects are laid under contribution. It would be quite impossible to enter here fully into the immense activities of Ichneumon Flies ; suffice it to say that most of the grubs and caterpillars that destroy cultivated crops are known to be attacked. The dried skins of Aphides containing the parasitic grub and forming a covering for it, can always be found in considerable numbers. In fact, practically all the more serious pests are destroyed by Ichneumons. Unlike the Ladybirds and Lace wings, of which the grubs are too frequently destroyed in ignorance, the large group of parasitic insects here called Ichneumon Flies need no special plea for their preservation, for in the early stages they are out of sight or not prominently noticeable, and as adults are active, watchful and able to take care of themselves. Description and Life History. The Eggs are deposited in or upon (usually in) the bodies of other insects by means of a special egg-laying apparatus. It is usually the egg, grub or pupa stage which is attacked. The Grub, with a few exceptions, is a whitish, legless maggot, like its cousin the wasp-grub in appearance but differing in size according to the species. In the case of the internal feeders, it lives on the juices of its prey which it eventually destroys, but not before it has itself become full-fed. In some cases, it leaves its prey and spins a cocoon itself ; in others it waits until its victim has spun a cocoon before killing it and then merely * For the purposes of this publication the designation " Ichneumon Flies " is made to cover the greater part of the Hymenoptera Parasitica as well as the Ichneumonidce, viz., Braconidce, Proctotrypidce, Chcdcididce,