®l|? i. 1. Bill Cibrarg ?Jiirtb (Earolina §tatp 3B767 C7 IIIIIH^ S00785131 P /J'^ :^'^'t^4*-T,>T>-'C'^-^ This book is due on the date indicated below and is subject to an overdue fine as posted at the Circulation Desk. BRITISH VEGETABLE GALLS ' Rerum Natura ; Plate i. A Birch-tree, Betiila alba Linn., Broomham Park, Guestling, near Hastings. (See page 55.) BRITISH VEGETABLE GALLS AN INTRODUCTION TO THEIR STUDY BY EDWARD T. CONNOLD ILLUSTRATED WITH ONE HUNDRED AND THIRTY FULL-PAGE PLATES AND TWENTY-SEVEN SMALLER DRAWINGS London: HUTCHINSON & CO. Paternoster Row . . . igoi PRINTED BY ;ELL, WATSON, AND VINEY, LONDON AND AYLESBURY. PREFACE. For several years past it has been one of my favourite pastimes to collect vegetable galls, and to observe the many peculiarities connected with their growth. The accumulation of a large number of specimens and a mass of notes resulting from these researches has awakened the desire to arrange them in book form. The purpose of this volume is not to deal exhaustively with the subject, but rather to afford the collector and the student a medium of reference, whereby about two-thirds of the number of vegetable galls at present discovered may be determined. Complete lists of all known galls are also given, with a brief description of each. The art of photo- graphy has been employed to represent the specimens as they appeared in a living condition. I have not attempted to produce pretty pictures ; my endeavour has been to arrange the specimens in such a manner that the various distinctive features of the galls themselves may be easily recognised. All the illustrations (except plate i) are my own production. No illustrations are given of the oak-galls. They will probably appear subsequently in a volume devoted exclusively to oak-galls. In giving the average dimensions of each gall, it has been con- sidered advisable to employ the millimetre as the unit (25 mm. =1 inch). Very much remains to be done in this section of natural history, and it is hoped that the perusal of the vi Preface following pages will act as an incentive to other students of Nature to continue their researches. My heartiest thanks are due to the Rev. E. N. Bloomfield, M.A., F.E.S., of Guestling Rectory, near Hastings, for the most valuable help and information which he has given me from the time I commenced the study of vegetable galls. I also gratefully acknowledge the assistance rendered in many details by my wife and my sons Russell Ernest and Harold Thomas. On several occasions my sons have discovered very fine specimens. Prof Dr. Alfred Nalepa of Vienna has kindly identified many of the galls caused by mites. Mrs. Coupland and Miss M. Bates have rendered invaluable service in translating Dr. Nalepa's works on Mites and his most helpful correspondence. To Mr. Frank B. Fermor I am deeply indebted for the time and patience which he has so kindly and unreservedly bestowed upon the correction and revision of the proof-sheets. I am also ver)' grateful to Miss R. D. Roff King for her valuable assistance v^ith the notes, photographs, proof-sheets, and various details connected with the compilation of the MS. For the gift of specimens I desire to thank most sincerely Miss Ethel Sayer, Rev. E. N. Bloomfield, Messrs. Frank Hall, R. R. Hutchinson, Walter Field, F. W. Terry, W. Furlonger, and G. C. Walton. 7, M.\GDALEN Terrace, St. Leonards ox Sea CONTENTS. Preface .... List of Full-page Plate.s List of Small Illustrations CHAPTER I. Wh.\t is a Vegetable Gall? . CHAPTER n. The Sizes, Shapes, and Colours of Galls . CHAPTER HI. The Collecting, Mounting, and Preserving Galls CHAPTER IV. The Emersion of the Lmagines CHAPTER V. The Mode of Growth and Classific.\tion of Galls CHAPTER VI. The Agents concerned in the Production of Galls The Root-galls 39 The Stem-galls S3 viti Contents PAGE The Leaf-galls 119 The Flower-galls 267 A Table of Months in which the Galls illustrated in THIS Volume may be Found 295 A List of Plants illustrated in this Volume . . . 298 Names of Makers of Galls not illustrated in this Volume 301 A List of Galls found on Quercus 305 A List of Works Consulted 307 Index 309 LIST OF PLATES. 1. A birch-tree in Broomham Park, Hastings . Frontisp, 2. Glands on petioles of leaves of Prunus avium 3. Thickened roots, or pseudo bulbs of grass 4. Stem of Betula alba, with aborted branches . 5. Collecting impedimenta used by the author . 6. Apparati employed by the author when photographing 7. Bottles, etc., used for rearing makers of galls 8. Brassica Napus, galled by Ceuthorhynchus sulcicollis 9. ,, rutabaga 12. Pyrus Mains 13. Potentilla reptans 14. Corylus Avellana i;. .. .. 16. Betula alba Populus tremula Salix Caprea „ cinerea Galium verum Salix Caprea Schizoneura fodiens Xestophanes potentill. ., „ macrorhyncus 14 58. Salix alba marginatus . 14 59- Pyrus communis piri . . ■ . i5< 60. Taxus buccata „ „ psilaspis . 15 61. Populus tremula pustulatum . ■5 62. Ribes nigrum II ribis . 15 63. Betula alba „ „ rudis . 15 64. Poterium sanguisorba „ sanguisorba; i6f 65. Prunus spinosa similis . 16 66. Salix Caprea „ tetanothrix laevis . 16. 67. Tilia europjea tetratrichus . i6f 68. tilias (typicus) 16 69. „ „ tiliarius 17c 70. Juglans regia „ tristratus, var. erinea 17 71. Viburnum opulus ,, viburni 17- 72. Fagus sylvatica Monochetus sulcatus . \ji 73- Acer pseudo-platanus Phyllocoptes acerirola . 17 74- Fraxinus excelsior fra.xini 1 8c 75- Juglans regia Eriophyes tristratus, var. erinea 18 75- Glechoma hederacea Aulax glechoma; . 18- 76. Crataegus Oxyacantha Eriophye goniothorax. 18. 76. Pyrus aucuparia aucupariae . 18. 77- Achillea millefolium Tylenchus millefolii . i8f 78. Glechoma hederacea Cecidomj ia bursaria 18 79- Crataegus Oxyacantha cratccgi 19c 80. Lathyrus pratensis lathyri •9 81. Salix viminalis marginem-torquens 19. 82. Polygonum amphibium persicaricc i9( 83. Pteris aquilina pteridis . 19 84. Ranunculus repens ranunculi . 20c 85. Salix aurita, Rosa canina Taxus buccata Spiraea Ulmaria Urtica dioica Veronica chamaedrys Viola canina Fraxinus excelsior Popuhis tremiila Salix Caprea Fagus sylvatica Achillea millefolium Fagus sylvatica Ranunculus repens Viola canina Atriplex angustifulia Stellaria holostea Juncus articulatus Populus nigra Ribes nigrum Ulmus montana „ campestris Gleclioma hederacea Salix Caprea „ fragilis Rosa canina List of Plates galled by Cecidomyia rosaria rosarum It t2xi ulmarise urticpe veronica; violcE Diplosis botularia ,, tremulas . Hormomyia capreae Fagi . millefolii piligera Polycystis pompholygodes ,, viola: . Aphis atriplicis Brachycolus stellariae Livia juncorum Pemphigus bursarius ,, spirotheca Rhopalosiphum ribis Schizoneura ulmi . Tetraneura ulmi . Aulax glechomae . Nematus bellus . „ gallicola . Rhodites eglanteria; „ nervosus rosae 123. 124. 125. 126. 127. 128. 129. 129. ,130. „ rubiginosa Rubus fruticosus Populus tremula Ajuga re plans Uaucus carota Betula alba Tilia europaea Vicia sepium Pyrus communis Arctium lappa Centaurea nigra Prunus insititia Lonicera periclymenum „ Papaver dubium and P. Rhi Prunus insititia Potentilla reptar.s A charming spot for galls ,, rubiginosK Lasioptera rubi . I liplosis tremulae . Eriophyes ajuga; . Asphondylia pimpernellae Cecidomyia betulae tilicola Diplosis loti . ,, pyrivora . Tcphritis bardana; Urophora solstitialis Exoascus insititise Siphocoryne xylostei s, galled by Aulax papa\ Exoascus insitiliae Xestophanes potentillce XI PAGE 202 204 206 208 210 246 248 250 252 256 258 260 262 264 266 266 270 272 274 276 278 290 292 292 294 LIST OF SMALL ILLUSTRATIONS. The millimetre scale Fig. I. A fine specimen of gall caused by Lasiopfera rtibi A. As growing. Natural size B. Longitudinal section. Natural size ,, 2. Urophora cardui A. The imago, x 5 B. The larva, x 10 c. Section of gall showing larval chambers. Natural size ,, 3. Leaves of Urtica dioka A. Three leaves showing under surfaces B. Upper surface of a leaf c. Lower portion of B, sliovving sections of galls ,1 4. Hairs from exterior of gall of Cecidomyia veronica: . „ 5. Portion of stalk oi Rantmcjilus repens twisted by Polycystis pompholygodes „ 6. Five stages in the spiral formation of a petiole of Populus nigra „ 7. Galls on stem and edge of leaflet of Rosa cattitia ,, 8. Thirteen galls on seven leaflets of Rosa canina „ 9. The gall and larva of Rhodites rosw A. The cells B. A fibre from exterior (enlarged) c. The larva, x 22. Ventral and profile views ,, 10. The gall of Urophora so/s(iiialis The gall with hairs, x 2 The gall denuded of hairs, x 2i Section showing larval chambers, x 2i The larva. x4. The pupa, x 4. facing 92 „ 96 242 256 256 260 284 BRITISH VEGETABLE GALLS. CHAPTER I. What is a Vegetable Gall? The Vegetable Galls constitute a branch of study and research that seems to have been much neglected by students of Nature generally. The galls, and the agents concerned in producing them, have not received the attention of botanists and ento- mologists which they deserve, since they are such valuable adjuncts to both classes of students and collectors. This is somewhat remarkable, since the botanist, while in pursuit of specimens for examination or the herbarium, must frequently find plants with galls upon them. The practical entomologist, in gathering the food-plants for the home-reared larva;, cannot fail to notice the deformities and protuberances on the leaves ; while if it be desired to secure the tiny Diptcra, Hymenoptera, and other imagines, in their pristine beauty, rearing from the galls is almost a sine qua tton. But there are persons who, in their study of Nature, have not met with galls, or if they have, little or no attention has been paid to them. Like all pursuits, when for the first time prominently brought to notice, the subject of galls and gall-collecting calls forth enquiries as to what they are, and where they are to be found. Before attempting to give a concise reply to the question. What is a vegetable gall? it will be as well briefly to consider the etymology of the word " gall " ; its history in English literature, in so far as it throws any light upon the answer ; and also to consider the opinions of some English writers who have given the subject their attention. 2 British Vegetable Galls The word " gall " is derived from three sources, and has many significations. The first comes from the Anglo-Saxon word " ge'lla" and, when used as a noun, denotes anything extremely bitter, the fluid secreted in the glandular substances of the liver being the most familiar example ; but under this derivation, when used in another sense, it denotes implacable enmity and spite. The next derivation is from the French word " galer" the active verb "to gall," and supplies a meaning to such expressions as to tease, to fret, to annoy, or harass a person ; it also implies a wearing away, or breaking of the skin by rubbing. The third is from the Latin "galla," and is used to signify the excrescences which make their appear- ance on various parts of many plants. It will not be difficult to show in due course how particularly applicable is the word gall, inasmuch as most kinds not only possess the bitterness of flavour which renders them objectionable to the palate, but, by their very mode of growth, tend to annoy and harass the vegetable substances upon which they may be found, causing them to bulge and swell to abnormal sizes, and producing deformities and con- tortions which are wholly foreign to all natural vegetable growth. Originally the word was used only in connection with a painful swelling, pustule, or blister in cattle, more especially the horse. In later use it indicated an external sore or wound produced by rubbing or chafing. With regard to the history of the word, the New English Dictionary informs us that the first mention of the word gall, as applied to the excrescences produced on trees, occurs in "Trevisa." Barth. De. P. R. XVII. civ. (Tollem MS.): "The mall (Mandragora) haf white leues . . . and apples growej) on fe leues, as galles growej) on oken leues." The next use of it was in 1440, and in 148 1 it was used by Caxton. In 1 562 Turner, in his " Herbal," ii. 109 b., says : " A gall is the fruite of an oke, and especially of the lefe." Fifty-four years afterwards Surfl. and Markh. in "Country Farme," p. 28, remark : " He shall know a fruilfull and fertile yeare if he see the Oke apples, commonly called Gals, a Flie engcndred and bred." In 1697 Dryden used the word, Virg., " Georg." iv. 389: "To these add pounded Galls and Roses dry." In What is a Vegetable Gall? 3 1776-96, "Withering British Plants" (ed. 3), ii., 388, it is stated that " the balls or galls upon the leaves are occasioned by a small insect with four wings." Tennyson, in 1842, speaks of a gall, " Talking Oak," 70 : I swear (and else may insects prick Each leaf into a gall). Most of these quotations without doubt refer to the oak- apple {Terns tenninalis). Probably only a very few of the other oak-galls were known prior to 1840. But for some years previous to that date the excrescences on other trees and plants had been noticed, and the word gall was brought into general use by English naturalists. The early writers on the subject of gall-growths appear not to have been able to determine how galls were produced, but were greatly puzzled to account for the ova and the larvae which they found within the tissues of the plant. It was supposed that the ova were deposited by the parent insect in the ground, and from thence drawn up with the sap and carried throughout the tree, until, having reached a certain point, the course was arrested, and the formation of gall-structure commenced. It was also considered possible that the larva, when newly hatched, ate through the cuticle of the leaf, and waited until the sap flowing from the wound enveloped it. Pliny (" Nat. Hist." xvi. 9, 10) was aware that flies emerged from gall-growths ; but, instead of associating the latter with the former, he thought that galls were of fungoid origin and grew as rapidly. J. Rennie ("Insect Architecture," vol. ii., p. 116) was aware "that the mother gall-fly makes a hole in the plant for the purpose of depositing her eggs," and also that "she is furnished with an admirable ovipositor for that express purpose " ; but he does not appear to have penetrated the mystery which then surrounded the development of their growth, for he proceeds to quote from " our older naturalists," that the parent fly "ejects into the cavity a drop of her corroding liquor, and immediately lays an egg or more there ; the circulation of the sap being thus interrupted, and thrown, by the poison, into a fermentation that burns the contiguous parts, and changes the natural colour. The sap, turned from its proper channel, extravasates and flows round the eggs, 4 British Vegetable Galls while its surface is dried by the external air, and hardens into a vaulted form." Many galls, however, do not begin to grow until the larva is hatched and commences to eat. Redi (" De Insectis," p. 233 et seq), not having witnessed oviposition by the parent fly, assumed that the " plant had a vegetable soul which presided at the origin of galls, with their eggs, larvae, and imagines, while it again gave issue to fruits." About the middle of last century the true nature of galls began to be understood. In Tomlinson's Cyclopaedia, published about 1850, in the section "Gall-Nuts," p. 735, the following appears: "These galls are produced by the punctures of an insect Cynips gallce tinctoricB, which deposits its eggs in the vegetable tissue, and thereby causes the shoot or bud to swell, and become an excrescence or gall, within which the larva is developed." Another publication of the same kind, in circulation about the same date, states that " galls are the result of morbid action excited in the leaf-buds of sev^eral species of the genus Quercus, or oak, occasioned by an insect Cynips quercus depositing its ova in the bud." Kirby and Spence (Intro, to " Entomology," ed. 7, p. 254), in describing " vegetable excrescences termed galls," state that "all these tumours owe their origin to the deposition of an egg in the substance out of which they grow." Rev. J. G. Wood (" Homes Without Hands," p. 484), after describing the operations of the parent insect depositing the ova, continues : " The effect of the wound is very remarkable. The irritating fluid which has been projected into the leaf has a singular effect upon its tissues, altering their nature and developing them into cells filled with fluid. As long as the leaf continues to grow, the gall continues to swell, until it reaches its full size, which is necessarily variable, being dependent on that of the leaf" Edward Steep was of the opinion that "the egg or the fluid which is ejected with it causes irritation in the plant, and an effort is made to cover up the annoying substance." Dr. Stratton (" Alternating Generations," p. 9) says : " A gall is an abnormal growth of plant tissue produced by animal agency acting from within." The " Encyclopaedia Britannica," vol. x., contains a long article on the subject. The following What is a Vegetable Gall? 5 has special reference to the point now in review : " What are commonly known as galls are vegetable deformities or excrescences due to parenchymatous hypertrophy. The exciting cause of the hypertrophy, in the case of the typical galls, appears to be a minute quantity of some irritating fluid, or virus, secreted by the female insect, and deposited with her egg in the puncture made by her ovipositor in the cortical or foliaceous parts of the plant. This virus causes the rapid enlargement and subdivision of the cells affected by it, so as to form the tissues of the galls. Oval or larval irritation also without doubt plays an important part in the formation of many galls. Though a certain relation is necessary between the 'stimulus' and the 'supporter of the stimulus,' as evidenced by the limitations in the majority of cases of each species of gall-insect to some one vegetable structure, still, it must be the quality of the irritant of the tissue, rather than the specific peculiarities of the part of the plant affected, that principally determines the nature of the gall." Other English writers might be cited, but to multiply quotations would be but to reiterate the same ideas. The opinions of French and German writers on the subject of gall formation are identical. These opinions only concern galls directly due to insect agency. The researches during the past few years in the department of agricultural zoology show us that many galls are due to the presence of nematoid worms within the tissues of the plants, and not only are they present upon the aerial portions of the plants, but are numerously disposed upon and within the roots. This latter fact — viz. the presence of galls on roots — does not appear to have been known to any of the early writers. This, however, is not the only agency unsuspected until recently. Various forms of fungi are now known to attack several parts of trees, and arc especially destructive to the fruits of the Frunus order. Some of the lower orders of plants also are considerably swollen, distorted, and their functions rendered ■ abortive, by the same cause. The boughs of fir-, beech-, ash-, and oak-trees are affected by fungi, and enormous gall-growths are oftentimes the result ; while the semi-e.xposed roots of ash- and birch-trees have been found distorted and swollen in a similar manner. 6 British Vegetable Galls There is therefore no warrant for restricting the term vegetable gall to an abnormity, the formation of which is due to cellular structure alone, or accumulation of sap alone, or even to insect agency exclusively, since other agents produce swellings which have the same appearance and cause like deformities of the plant. Nor does the etymology of the word permit such limitations. Henceforth the words must spread over a wider range of meaning — a meaning which can be defined, and a range which can be limited only by the systematist. How, then, shall a vegetable gall be described ? What is a vegetable gall? It is a morbid enlargement of the affected part of the plant, due to parasitic agency. Very few of the higher forms of plants are altogether exempt from the attacks of gall-producers. Fungi and lichens, however, do not appear to be attacked, although there is no apparent reason why these lower forms should enjoy immunity. The formation of a gall takes place only while the plant is in a growing condition ; but the death of the plant is not always an indication that the primary purpose of the gall should cease : so long as sufficient moisture is contained within the tissues of the gall, or that its external crust affords sufficient protection, so long is it fulfilling its main use. Some galls bear no re- semblance to the portion of the plant upon which they are situated ; but there is generally some organ of the plant, modified upon the exterior of the structure, which imparts a distinctive form. The most remarkable illustration of this feature may be seen in the fibrous covering of the Bedeguar gall {Rhodites roses), which represent fibro-vascular bundles of leaves with scarcely any parenchyma uniting them. In degree of complexity of internal structure, galls vary con- siderably. Some are quite simple with thin walls — eg. Nematus bellus, in which the larva feeds voraciously upon the interior until it has a mere shell for a covering, and this it leaves to pupate. Other kinds of a more solid nature have several layers beneath the epidermis, and a central cavity in which pupation takes place. Under such conditions the imago is provided with powerful jaws with which to eat its way out. The characters of galls are remarkably constant, and, as a rule, exhibit certain diagnostic features, some of which are obviously due to the act Glani.s on I'lniMii,.^ OF Leaves of Prinms aviii (NEARLY NAT. SIZE.) Specimens gathered at Hastings by the Author. What is a Vegetable Gall? 7 of oviposition, and not to the functions of the parts of the plant upon which they develop. There is a remarkable similarity of form in the galls produced by the EriopJiyida;. The larvae of some species of the same genus of insects cause galls which are totally unlike each other. Urophora cardui deposits ova in the young shoot of the thistle, and a succulent, glabrous, external swelling develops. U. solstitialis oviposits in the flower of Centaurea Tiigra, and the result is a very hard, hirsute formation completely obscured by the florets. Rhodites nervosus oviposits in the under surface of a rose leaflet, and a unilocular, globular, pedunculated larval chamber grows therefrom ; but R. spinosisshnce performs the same operation, and the leaflet itself bulges out on both surfaces to so great an extent that the serrations of its margins are scarcely perceptible. Other instances of the same phenomenon will present themselves to the collector in the course of investigations. No kind of British vegetable gall appears to be of any service to man in arts or manufactures ; nor are they suitable for food. Birds do not eat them, but when food is scarce in winter time, the small birds (Tits) remove the woody exterior of several kinds to get at the larva, which is then devoured. About 270 kinds of British vegetable galls are known. Reference may here be made, and illustrations introduced, to show various growths on plants known as glands, lenticles, etc., which are like galls and are misleading to the novitiate gall-collector. They are not due to parasitic agency, and do not contain ova or larvce. The glands on petioles of Pnuius avium (plate 2) are well defined. Glands as formed on plants are of various shapes and sizes, and of four principal kinds. They occur mainly on the various parts of the leaf, and appear in the form of sessile or pedun- culated, wart-like bodies, or embedded in the tissues of the plant, and occasionally contain a resinous or oily substance. A rather loose cellular tissue without epidermis is one of their chief constituents. The tuberous formations of petioles and roots of various plants demand a passing notice. Among the pond weeds there are several whose underground 8 British Vegetable Galls shoots terminate in a tuber, which in Scirpus lacustris Linn, may be as large as a chestnut, and in Sagittaria sagittifolia Linn, the size of a hazel nut. Similar features are also found in the bulbous herbs, Scilla nutans Sm. as an example, and in the orchid family also. The nodulose growths on roots of Spiraa are conspicuous examples ; but a more familiar example is seen in the thickened roots or pseudo-bulbs of grass. They may frequently be noticed on roadside banks, where the crumbling away of earth leaves them exposed to view ; and while in a semi-buried condition they look very like gall-growths. Some specimens are hollow, and closely resemble the empty larval chamber of a true gall. Two specimens of this kind may be seen in the right-hand side of plate 3. Peculiar swellings of the wood and the bark are also shown on plate 4. mm MILLIMETRE SCALE Plate 3. Thickened Roots, or Pseudo Bulbs of Grass. (NEARLY NAT. SIZE.) Specimens gathered at Hastings by the Author. Plate 4. Stem of Birch, Betiila alba Linn., Three True. and Twelve Aborted Branches. CHAPTER II. The Sizes, Shapes, and Colours of Galls. The chief interest in galls lies in the formations themselves, and not in the creatures which cause them. Yet the galls and their producers are so inseparably associated, that a study of one carries with it a knowledge of the other. This fact is very clearly illustrated when considering the sizes of various galls. It would naturally be expected that the more diminutive the creature the smaller the gall, but this is not always so. The ? imago of Pliyllocoptes accricola is 120 yit. long and 46 /i. broad (/it. = roVrith part of a millimetre). It is one of the smallest of the mites. They live upon the leaves of Acer pseudo-platamis. A few of them will cause the growth of and live within a globular-shaped gall not more than 3 mm. in girth. Eriophyes tilice iypiciis is a much larger mite. The ? is 200 fi. long, 35 /i. broad, yet it causes and lives within a hollow conical gall 8 mm. high and 6 mm. in girth at the base. E. orientalis lives on leaves of Cydonia vulgaris, in hollow scabious pustules of the same size and character as those caused by E. piri on pear leaves. The ? of E. orientalis is 270 /i. long and 55 /A. broad. It is next to the largest of all the gall-mites. But what these creatures lack in size they supply numerically, and when thousands are living upon any particular portion of a plant, the galled area is proportionate. Examples of such are furnished by E. inacrorhynchus, E. piri, and E. lu-vis, the multiplicity of whose galls oftentimes absorbs an entire leaf. Among the Diptera a similar disparity is manifested between the size of the gall and the imago issuing therefrom. The action of three or four larvse of Urop/wra cardui in the stem of Cardiius arvensis will produce a more or less globular, 9 lo British Vegetable Galls succulent gall 24 mm. long and 70 mm. at its greatest girth, whereas the same number of larvae of Urophora solstitialis living at the base of a flower-head of Centaurea nigi-a will cause a hard and woody gall 10 mm. high and 20 mm. in girth, con- siderably less than half the bulk of the other. The imagines of both species are the same size. One larva of Honnomyia Fagi will cause a hollow cone- shaped gall on a leaf of Fagus sylvatica 4 mm. high and 4 mm. in girth at its base ; one larva of AspJwndylia pimpcrnellce will cause a hollow, reniform gall 8 mm. long and 15 mm. at greatest girth on the umbels of Dancus carota. There is scarcely any difference in the size of these imagines. Of all gall-producers the Eriophyida live together in greatest numbers. A leaf-bud of Corylus Avellance or Ribes nigrum in the summer time will contain hundreds of the creatures in each of their stages of growth ; while on such masses of deformed and stunted growth as illustrated in plate 62, the mites would possibly number hundreds of thousands. The number of separate cells, or larval chambers, varies greatly. A large proportion of galls are unilocular, and are seldom of any remarkable size, but the largest number are multilocular. Most of the latter kind are composed of 3 to 8 cells ; but in Rhodites roses there may be from 30 to 50, Atdax papaveris 40 to 60, and Diastrophus riibi 80 to no. These cells are all included within one outer covering, whether it be a coating of long hairs, a seed capsule, or the epidermis of the stem. The smallest unilocular gall is the pustule form caused by Eriophyes macrorhyncus. They are very numerous on the leaves of Acer campestre. The largest is that caused by CeiitJiorhynchus siilcicollis on the root of Brassica ttapus. The gall caused by Lipara lucens on Anindo Phragmites would appear to be larger, but its additional bulk is due to the numbers of leaves which enfold one another, and enclose a relatively small larval chamber. The shapes of galls vary greatly. About eighteen definite forms can be recognised. Globular, or more or less so, is the shape of the majority. Many are reniform, not only as a single growth {^Eriophyes macrocJichis), but in clusters {Xestopha/ies brevitarisis) on a The Sizes, Shapes, and Colours of Galls 1 1 stalk, or arranged along it in a moniliform manner. Several are cigar or torpedo shape, or lemon shape ; others are pyriform, bursiform, hemispherical, sessile, or pedunculated. Two at least are rosette in form ; and although one, Cecidomyia craUegi, is exceedingly common, it commands as much admiration as does C. rosaria, which is far less plentiful. A few conical forms appear usually on the leaves. Others are pyramidal, spindle shape, or ovid, and several are pineal in form. One at least {Monochetus sulcatus) is cymbiform. The remainder are ir- regular in outline, being constricted, curved, or dwarfed during growth. The galls formed by Rliodites nervosus have sharp- pointed spines or thorns on the surface, and in this respect they are unique. The colours are not so numerous as the shapes. Many galls have most delicate and exquisite shades of colour when nearing maturity of growth. The predominant colour is green, very delicate shades of which may be seen at various stages in the growth of the galls ; in fact, as may be supposed from the positions occupied, they are all more or less green, changing only as they approach or attain maturity. Some galls are of very sombre hues, un- relieved by any colour at all ; others have no definite colour, other than green ; a large number, however, are very bright and attractive. Greens of every shade, from a very pale yellowish to a rich olive, are common. Yellows, from a very pale tint passing through all shades until a deep orange is reached, are not so numerous. Reds, from a faint pink blush to a purple or reddish brown which quickly passes into a chocolate-brown are less plentiful. Many galls at first are suffused with pink, which, as growth proceeds, deepens to red, then to purple or reddish brown, and finally chocolate-brown or black. One kind only is silvery white, and remains so until maturity is past. It is caused by the larva of Hcdya accriana on twigs of Populus alba. The gall caused by the larva of Eurytoma hyalipennis is remarkable in gradually losing its colour as growth proceeds. At first the young leaves are striped with pink ; this gradually becomes paler, until ultimately the entire gall is an ordinary straw colour. Very few are like Cecidomyia pteridis, which, beginning as a very pale green, 12 British Vegetable Galls soon turns black. Asplwndylia pimpeniella is at first a pale green, upon which, as it changes to a much darker shade, pink stripes appear ; these stripes deepen in colour before maturity of growth is reached. The galls on the leaves of Acer pseudo-platanus caused by Phyllocoptes acericola, and Eriophyes macrorliyncus on Acer canipcsti-e, are very attractive. At first greenish yellow, they pass through yellow, orange- yellow, red, crimson, purple, and finally brown. Those caused by Cecidomyia persicarice are very beautiful. The rolled and thickened margins of the leaves of Polygonum ampJiibiuiii are a much paler green than the other portion of the leaf, and are suffused with pink and purple, which does not change until the leaf withers. Those of Tetranenra ulmi are also very attractive, standing upright upon the rich green Elm leaf. The colours of this pedunculated, pyriform gall are pale yellow at base, with pink gradually taking its place higher up, and a bright crimson at the apex. Aulax glecliojiicB is another charming growth. The bright pink or red globular galls are clothed with long, slender, whitish hairs, and when seen nestling among the beautiful green leaves of Gleclioma hederacea on a wood-side bank, they never fail to excite admiration. The exquisite delicacy of the stems and leaves of Potentilla tormentilla is more apparent when numbers of the pretty little globular or reniform galls caused by the larva; of Xestophattes brevitarisis adorn them. At first pale green, they quickly assume a pink tinge, which changes to nut-brown when mature. The larvas of Nematiis bellus cause some delicate globular or conical sessile galls on the under surface of leaves of Salix Caprea. At first they are pale green, then greenish yellow, upon which red or reddish brown spots appear, and the surface, sometimes glabrous, sometimes sparsely clothed with delicate whitish hairs, produces a pretty contrast against the beautiful green of the leaf. Few galls, however, equal in attractiveness and beauty those caused by the larvse of Rlwdites rosce. From the surface of the conglomerated cells a dense covering of long, many branched, hair-like bristles proceed. These beautiful green, pink, and crimson hair-like or moss-like masses produce an unmistakable and unique appearance. No collection of galls is complete without speci- mens of this most familiar example. Plate 5. The Collecting Impedimenta used bv the Author. Explanation of Figures. Vasculum, with broad shoulder-strap. Notebook, with pencil. Three-inch rule. Cyanide bottle. Small pocket tins and coil of string. A tin, 12 X 9 X 8 inches, to contain most of the implements and the specimens. Small entomological leno-net. Newspaper, in which to wrap plants with roots and earth. Steel blade fern-trowel. Leather sheath for same. Supplementary knife. Curved handle walking-stick. Hop-knife, with narrow leather strap attached. Small tenon saw, with edges protected by piece of wood. Piece of common tallow candle. A broad leather strap for tin (f). Canvas bag, with handles of webbing suspended from lid of tin (f). CHAPTER III. Collecting, Mounting, and Preserving Galls. No person of average health and strength need refrain from collecting galls. It is as suitable a pastime for ladies as for gentlemen. It is not laborious work. It does not cause fatigue, such as results from chasing Lepidoptera, Diptera, Hymenoptera, etc., nor is it exposed to the fun and jest from the " vulgar mind " so often hurled at the collector of winged insects. It develops and quickens the powers of observation when in the fields, lanes, and woods, and combines the twin studies of Entomology and Botany. An extensive knowledge of these studies is not absolutely necessary, but a general knowledge of the different orders of insecta and of the habitats of plants is very desirable, and will often save hours of fruitless search when wishing to acquire a particular gall on any given plant. E.g. it would be useless to search for the galls of Eriophyes sanguisorba; in a district where the ground is marshy ; the salad burnet {Poterium sanguisorba) grows only in dry pastures in limestone districts ; nor would the galls of Cecidomyia ulniaricB be found on the hedge-bank of a dry and dusty road ; Spircea Ulmaria delights in wet and marshy places, and along the banks of streams and margins of ponds. Much useful information may be easily obtained from handbooks dealing with both these subjects. The Impedimenta requisite for collecting are neither ex- pensive to purchase nor heavy to carry, and need not be elaborate as regards the number of articles used. Each collector soon finds what the requirements for such purpose will be. As a guide to the beginner in the collection of galls, the Collecting, Mounting, and Preserving Galls 15 articles enumerated on p. 13, and illustrated on plate 5, are suggested as being suitable. When searching over new or little-known ground, it is advisable to be provided with all the tools. It is not possible to foretell what may be discovered, or which implement will be required. When only one or two specimens of the various galls are required, a small vasculum, such as A, is sufficient, which, if fitted with a broad shoulder-strap, is no trouble to carry ; but if the gallist's object be to make an extensive collection, or to copy or photograph the various forms, sizes, and aberrations of galls in the manner exemplified in this volume, it is necessary to employ a more spacious receptacle for the specimens. If the beginner is not already familiar with the fact that most plants when carried in the hand during a hot day quickly fade and droop, some never to revive again, one experience will perhaps suffice to show the advisability of having a tin with a lid to it : for, although the specimens are put in the tin, a midsummer sun will speedily cause them to wither, unless protected by a closed lid. This tin (f) may with advantage be of sufficient size to hold all the articles enumerated. One of the most necessary articles for the gallist to have is a strong and sharp knife, of any pattern preferred. The pattern of knife the author has found most serviceable is that known as a hop-knife (m) with a wooden handle. Into the end of the handle a screw-eye is fixed, to which is attached one end of a narrow leather strap, the other end of which is formed into a loop sufficiently large to pass over the hand. By this means the knife is tethered to the wrist, and, when not being used, both hands are left free for turning over leaves, etc. With ordinary care the chances are very few of being cut by the unprotected blade. The short-handled entomological leno-net (g) and the cyanide bottle (d) may not be required by some collectors ; the author, however, has repeatedly found them of the utmost value during the months when insects are on the wing. When on a long expedition, a small tenon saw (n), with the edges protected by a slip of wood, should always be carried. Small boughs and young saplings are more speedily and easily severed with it than with the knife. A small piece of common 1 6 British Vegetable Galls tallow candle (o) rubbed on the saw when used upon green wood will facilitate the work and prevent "binding." A walking-stick (l) with a curved handle is very useful in reaching high branches. The collector, however, may dispense with it, and rely upon cutting a crook bough from a hedge or wood when required. One or two pocket -tins (e) for small or fragile specimens are of great service ; as also is a coil of stout twine. A note-book and pencil (b) are absolutely necessary. Particular spots where galls have been or are to be found should be entered, with dates when found, or when the places should be revisited to observe developments in growth, or to remove the specimens under observation. Rough outlines of the places, such as will refresh the memory and act as guides without loss of time, are also of great value. Collecting. A considerable amount of patience and leisure is required for collecting galls. They are seldom seen, and less seldom found, while walking quickly. Examples such as Eriophyes rudis on birch-trees, and Cecidomyia cratcegi on almost every wayside hedge, are among the exceptions. They are too large and too conspicuous to escape observation. It is often necessary to crawl on hands and knees, using the eyes diligently at the same time. At all times it is best to saunter along the hedge or bank, by the stream, across the field, or through the wood, and by retracing your steps specimens will occasionally be found which have been previously undiscernible. When searching over a bush, such as a willow, it is advisable, after examining the inner boughs, to walk all round it two or three times, scrutinising on the first occasion the boughs nearest to you, and on the next round those farthest from you. Oftentimes a gall which cannot be seen from one side of a bough, twig, or leaf, may be detected from the opposite side of the bush. Fix the eyes on a branch, bough, or twig, and look carefully up and down it before passing to another. Looking at them with the sky as the background is a great help in discovering abnormal swellings. Many kinds of galls can be easily seen by stooping, or even lying down, and looking at the shrubs or bushes from beneath. This is particularly applicable to the Rlwdites galls when the wild rose bushes are in leaf A windy day is not recommended as a suitable occasion on Collecting, Mounting, and Preserving Galls 17 which to search for galls growing on bushes and trees. The continual movement of the foliage makes detection very difficult and wearies the eyes. An attempt has been made in each synoptical table to direct the collector to the most likely places in which the galls are to be found, and for further information in this section reference thereto must be made. Mounting galls and the imagines which emerge from them may be accomplished in various ways. The particular method of arrangement in the cabinet or wall-case may be left with the galiist to adopt which ever is most suitable to the conveniences at command. One thing is most essential : the galls should be allowed to dry thoroughly before placing them in their final positions. The following suggestions may prove useful to the galiist who has not decided upon any definite plan of arrangement. A small label should be affixed to each specimen, or cluster of specimens, bearing (a) name of plant, (d) name of creature producing the gall, (c) locality where found, (d) date of find, (e) a number corresponding with the same in note-book or catalogue. Imagines of average size may be fixed on a small piece of white card, or put in a small glass phial, which has upon it a number corresponding with that on the label and date of emergence. Parasites and inquilines should be put in a separate phial labelled accordingly, and placed by the side of that containing the imagines. Very small imagines which require a lense or microscope for their examination may be mounted in the following manner. Cut a piece of card, of about double the thickness of a post- card, the same size as a microscope glass slip — viz: 75 mm. x 25 mm. — and with a steel punch of 12 mm. diameter make a hole in the card. A slight burr will be caused on the under surface of the card, which should be removed with a sharp knife or rubbed down with the thumb-nail. This surface of the card must then be seccotined, and one of the glass slips placed upon it and allowed to dry. When dry, affix a name-label on the card, fill in particulars such as have already been suggested, and then place the creatures in the cavity of the card. Seccotine the outer margins of the card, and place the other slip on, and 1 8 British Vegetable Galls set aside to dry, with a small weight on it to keep it flat and firm. By using two glasses any part of the creature can be easily examined. The glasses should be carefully cleaned before the creatures are placed in the cavity. Microscope slips may also be obtained with cavities of various depths in them, in which the creatures can be placed, and kept secure by a cover slip affixed, and ringed in the usual manner. This kind obviates the necessity of card. When a large number of any of the small-sized galls can be obtained, it is preferable that they should be mounted in shallow wooden trays with glass tops, rather than occupy a quantity of space in the cabinet. The trays should measure 10 in. long, 7 in. wide, and 2 in. deep inside, with sides ^ in. thick. The glass lid should fit dust proof The interior may be papered or painted white, cream, or French grey, one corner being partitioned off to form a carbon cell. The outside can be polished, painted, or covered with black paper. The advantages with these cases are that they save cabinet room and floor space, can be hung on a wall, and easily removed for examination or exhibition purposes. Galls produced by Lasioptera rubi, Diplosis tremidcB, Pemphigus biirsanus, Nematus belltis, and others are very suitable for mounting in this manner. For larger galls, such as those caused by Scki::oneura lanigera and Eriophyes rudis, glass-fronted cases i8 in. square and 4 in. deep inside will be found a very suitable size. The specimens must be fastened in their places, and may be pinned or scccotined, according to their requirements. Large and heavy galls should be held by screws. This arrangement is very suitable by which to exhibit the aberrations from the type form, immature growth, transverse and longitudinal sections, and any other feature which it may be desirable to illustrate. To prevent mites, which are so destructive in all collections of natural history specimens, the cases should be kept replenished with albo-carbon. It is inexpensive, and may be obtained at almost any ironmonger's or oil-shop. Preserving galls in their natural beauty is a very difficult matter. There does not appear to be any known or recognised method by which they can be preserved from shrivelling and loss of colour. If gathered when mature, the hard and woody Collecting, Mounting, and Preserving Galls 19 kinds do not alter very greatly. The succulent kinds, however, shrivel quickly and lose their colour. It does not seem to be possible to preserve their colours nor shape in any way com- parable with their pristine condition. A few experiments with fluids as preservatives show that methylated or even pure spirit is of no value, as it extracts the colours. Pure glycerine, or a mixture of equal parts of glycerine and water, is of little value. Solutions of corrosive sublimate, and also of formalin, are not always successful, for in many cases the leaf, the stem, or the gall itself loses more or less of the natural colours, and then the true value is deficient. PLATE 6. Explanation of Figures. Three ordinary wooden broom-handles fastened to a 5-in. triangular- shaped platform 2 in. thick, held more rigid at 18 in. from the ground by a similar shaped but larger platform, which causes the feet to spread 12 in. apart. A 2-ft. length of broom-handle which slides up or down through the top platform. A bent spring, pressing against d to retain it at any height required. A long strip of black cloth wound round the top of D, serving the purpose of a pin-cushion. Pins of various makes, thicknesses, and lengths. A cross-bar of wood, having square sides ; one end encircled with a padding of black cloth, the other end having a wooden pin pro- jecting downwards at right angles. The padding of clotli upon which specimens are to be pinned. The wooden pin, 2 in. long, descending in a hole prepared for it in the top of D, and allowing h to revolve when necessary. An accessory to take the place of H when required. It is cut in the centre for holding twigs or branches at any angle necessary. A pair of small pliers, useful in manipulating the pins. Brass forceps, for suitable arrangement of leaves. Strong, blunt-pointed scissors, for cutting twigs. Fine-pointed scissors, for removing leaves which obstruct view of galls. String, useful in numerous ways. Plate 6. The Apparati employed by the Author when photographini; the specimens. CHAPTER IV. The Emersion of the Imagines. This branch of the study of vegetable galls is beset with many difficulties and attended with very variable successes. The emersion of the imagines is of very great importance to the gallist, especially with new forms of galls, but it is often very disappointing in its results. Half-grown galls cannot be relied upon to complete their growth under artificial conditions and yield the imagines. Some may continue to grow, others will speedily shrivel. To remove the plants to your garden, or in pots in your con- servatory or study, is perhaps the best plan to ensure their continued growth ; but the artificial surroundings are not always suitable, and " something goes wrong." Greater difficulties have to be overcome as regards galls growing on bushes and trees. One exception to these, however, is found in the willows, the twigs of which, if gathered in the early spring and put in water, will throw out a number of rootlets, the catkins and leaves unfold, the galls arrive at maturity, and the twigs themselves may afterwards be planted in pots or in the open ground. The succulent summer galls require great care. Those of the autumn are more trouble, and seldom yield any satisfactory results. Each twig bearing a gall which shows a difference from any others of the same species should be kept separate, and for such purpose the ordinary medicine and perfume bottles are very suitable. When these conditions are not possible, none but mature galls should be gathered. Those which do not require moisture to keep them in such a condition as to allow the 22 British Vegetable Galls imagines to make their way out, may be put in a glass-top box, a bottle, or glass jar. The neck of the bottle should be closed with a plug of cotton wool and the mouth of the jar covered with leno or tulle. Others requiring moisture should be put in a glass jar which has a depth of about an inch of sand or earth at the bottom. Nothing besides the galls and a label should be in the jars, or other insects may appear from buds, leaves, petioles, etc., and cause confusion in determination. The sand for this purpose must be thoroughly washed and baked. The earth also must be baked. This will destroy minute organisms which might grow and disturb the accuracy of the observations. Both the sand and the earth should be moistened with water which has been boiled and allowed to get cold. The addition of two or three drops of carbolic acid to each wineglassful of water will still further prevent the possi- bility of fungoid growths. Do not remove the galls as soon as the first imagines appear. Parasites and inquilines, and sometimes hyper-parasites, appear a long while afterwards, and these are also required for identi- fication. Small plants such as the violet, wood hawk-weed, veronica, bedstraw, etc., should be dug up (with as much earth as convenient left around the roots), wrapped in paper, and replanted upon the return home. All leaves not galled should be carefully removed. When specimens growing on trees are of the kinds which will not continue their development after being removed from the tree, it is advisable to place over them a bag of leno or tulle, and secure it to the branch with fine string in such a manner as to prevent the escape of the imagines. The spot should be visited frequently to make observations, and to renew the leno if damaged by wet or other causes. Imagines of large size, as compared with the average gall-producers, are the easiest to rear. Little difficulty is experienced with Uropliora cardui, Rhodites rosce, and Aulax gkchoma;, provided the galls are gathered at the right time. The galls of the Eriophyidce always contain imagines, as also individuals of the previous stages, and may be gathered at any time. The methods of securing the imagines upon emersion are PtATE 7. Bottles, Jars, Glasses, etc., used for rearing THE Makers of Galls. The Emersion of the Imagines 23 numerous. Each class of gall requires some variation in its treatment, as compared with that of another kind. Some galls may be put in a box with a glass lid ; others must have earth for the larva; to pupate in ; some require a bag of leno of very fine mesh tied over the twig ; other imagines are captured best in a lamp-chimney, with leno or tulle stretched across one opening, the galled leaves or twigs being placed in the other end, both then being stood in a glass of water. Some galls require the influence of the atmosphere, and must be kept out of doors ; to other kinds this is quite immaterial. Very small galls may be put in glass phials, kept in an upright position by being sunk in a block of wood, as shown in the centre of the illustration (plate 7). In every case it is necessary to put a label in the bottle, box, or jar, with the date when the specimen was placed there and other items of reference. They must be examined each day, and upon the first sign of decay, or growth of fungus (which has the unfortunate habit of appearing when least expected and of growing very rapidly), they must be removed, and various expedients adopted to prevent the galls becoming useless. CHAPTER V. The Mode of Growth and the Classification of Galls. The remarkable diversity in the shapes and sizes of galls is surpassed by the many and various manners in which they grow, and the positions which they occupy on the plants and trees. The mode of growth is very interesting, and should be carefully observed and thoroughly noted by the student and collector. Galls may be found on every part of plants and trees, from the roots to the flowers and seeds. When upon the roots, trunk, branches, twigs, stems, stalks, or leaves, their growth does not interfere with the fructification of the plant, nor, as a rule, with its general development ; but when the petals, seed-vessels, or other reproductive functions are involved, injury of a more or less derogatory character is the result. The following are the predominant modes of growth with typical examples of each, which galls assume. The charac- teristic features give to each growth an individuality which is valuable in one method of classification. I. Axillary = Eriophyes axillaris. IX. Hirsute = Rhodites roses. II. Coalescent = Hormomjia cap- X. Imbricated = Adelges abietis. rem. XI. Pedunculated = Teiraneura III. Conglomerated = Diastrophus iilmi. rubi. XII. Pilose = Aulax glechoma;. IV. Cymbiform = Monochetus sul- XIII. Pubescent = Hormomyia pili- catus. gera. V. Elongated = Diplosis botularia. XIV. Pustulate = Eriophyes pustu- VI. Glabrous = Diplosis tremula:. latum. VII. G\ossy = Urophora cardici. XV. VMgost = Aulax hypocharidis. VIII. Gregarious = Phyllocoptes ace- XVI. Rosaceous = Cecidomyia ro- ricola. saria. The Mode of Growth and Classification of Galls 25 XVII. Scabious = Schizotuura lani- XXII. Rolling and thickening of the gera. leaf = Ceddomyiapcrsicaria. XVIII. Se^ardXe. = Asphondylia pirn- XXIII. Upon the upper surface of pemeUte. the leaf = Eriophyes tilia: XIX. Sessile = Cecidomyia ulma- lypicus. ri(g_ XXIV. Upon the under surface of the XX. Solitary = Eurytoma hyali- leaf = Nematiis bellus. petinis. XXV. Upon the margins of the leaf XXI. Spiny = Rhodites nervoms. = Eriophyes marginatus. This list does not include all the different modes of growth, but the few remaining are more of the nature of variations from a given form, and do not convey any idea of individuality, being very irregular in outline and arrangement. E.g. the gall caused by Cecidomyia taxi might be classed as an imbricated gall until a dissection is made of it ; it will then be seen that the leaflets are imbricated, and not the larval chambers, as in Adelges abides, the larva being ensconced in a small cell at the bases of the leaflets. The gall therefore is solitary and unilocular. The Classification of Galls. Hitherto there does not appear to have been any special system adopted by English writers for the classification of vegetable galls. There are, however, several ways in which they may be classified, among which are the following : I. According to the natural order in the animal world of the creature which causes the growth and issues therefrom. II. According to the botanical order of the plant upon which the gall grows. III. According to the situation of the gall upon the various organs of the plant. IV. According to the mode of growth of the gall. V. Whether the gall consists of one larval cell only, or of two or more larval cells. VI. Anton Kerner, in his "Natural History of Plants" (translated from the German by F. W. Oliver, M.A., D.Sc), makes two broad primary groups— simple and compound. By simple is meant when a gall-growth is limited to a single plant-organ. This group is subject to three sub-divisions. {a) Felt galls, which are due chiefly to hypertrophied epi- dermal cells growing out into hairy coverings, of various sorts, The majority of these are caused by mites. 2 6 British Vegetable Galls {b) Mantle galls. These are hollow, in a multiplicity of forms, and have for a lining a portion of the surface of the affected organ, and in many cases a cavity or open communi- cation. {c) Solid or tubicular galls, in which a spot is pierced by an insect and the ova deposited in the tissues, not on the surface. These differ from mantle galls in that there is no cavity nor opening, the imago having to bore its way out. They are, however, subject to numerous modifications. The other group is composed of compound galls, and com- prises those in which several plant-organs are concerned in the production. They are arranged according to structure, and named scroll, pocket, and covering galls. It will now be necessary to review these various methods of classification, in order to form a judgment as to which is the least involved, and at the same time the most efficient. I. According to the natural order in the animal world of the creature which causes the growth and issues therefrom. It is not in every case possible to determine from the gall alone what creature has caused its growth, more especially in the case of galls found for the first time by the gallist, or new to science. The difficulty of keeping the gall in a living con- dition until the emersion of the tenant has to be overcome. And supposing this to be successfully accomplished, not the rightful inhabitant issues from it, but parasites, inquilines, and hyper-parasites are very frequent, and the difficulty of assigning them to their respective families is considerable. Sometimes the rightful inhabitant itself dies within the gall. Yet another difficulty presents itself: the larvae of many species leave the gall to pupate either some distance away or in the earth, and they invariably die when kept under artificial conditions. II. According to the botanical order of the plant upon which the gall grows. A classification of galls under this head is too elaborate. There are about a hundred natural orders into which the British flora is divided. An arrangement based upon so many sections is suitable only for a very large and comprehensive, world-wide collection. III. According to the situation of the gall upon the various organs of the plant. The Mode of Growth and Classification of Galls 27 While neither adapting itself to every requirement, nor satisfying each detail, a classification based upon the position the gall occupies upon the main divisions or organs of a plant appears to fulfil nearly all the necessary qualifications in as comprehensive a manner as possible, and to provide a basis upon which the gallist can construct any more elaborate system which may be thought desirable. IV. According to the mode of growth of the gall. Although this would not be so extensive as No. II., a classification based upon the twenty-five or more different modes of growth, is too wide in its scope to possess the advantages offered by one of a more concise character. Some galls which during their earliest stages of growth are glabrous become pubescent before attaining maturity. Some which are sessile while growing ultimately assume a pedunculated form. Others which on one portion of a leaf will be separate, are gregarious and coalescent on another part of the same leaf. In fact, no reliability can be placed upon the features, which are quite of a secondary character. V. Whether the gall consists of one larval cell only, or of two or more larval cells. Most descriptions of galls have been based upon the number of the cells or larval chambers. The terms which have thus been employed are unilocular, or monothalamous ; and plurilo- cular, or polythalamous. A unilocular gall consists of a definitely formed separate cell, solitary or gregarious, embedded or not embedded in the tissue of the plant, and irrespective of its size, shape, or the position which it occupies on the plant. A plurilocular gall consists of two or more cells, coalescent or conglomerated, embedded or not embedded in the tissue of plant, and irrespective of their size, shape, or the position which they occupy on the plant. There are several objections to a definite classification according to these terms. The larvje of some species do not inhabit a definitely constructed cell, yet they produce gall-formations. Many galls which, when occupied by the rightful larva, are unilocular, become plurilocular when the larva or larva; of parasites also inhabit the gall. Other galls which normally consist of a single 28 British Vegetable Galls cell are occasionally so numerous and crowded together that they coalesce, and the final condition is plurilocular. The hypertrophied growths caused by various fungi are destitute of larval chambers. As an adjunct to the description of a gall when applicable and to indicate the normal number of cells of which it should consist, these uni- and plurilocular designations are of considerable value, and for that purpose alone they are used in most of the following synoptical tables. VI. Anton Kerner's method of classing all galls under two main divisions, simple and compound, divided into various sub-sections, is excellent, but the numerous modifications which are necessary do not appear (in our opinion) to be defined clearly enough for actual use. Neither are the terms applied to the galls so suitable as might be employed, nor calculated to be of much assistance to the beginner. Several of the foregoing nomenclatures do not possess all the qualifications suited for a lucid and comprehensive description of vegetable galls. As the result of an examination of hundreds of galls and a thoughtful study of the various classifications, the author has arrived at the conclusion that a definite, yet simple, accurate, and easily remembered nomenclature is the great desideratum which requires supplying in this branch of natural history. It is therefore proposed that galls shall be classified according to the positions which they occupy on the plant ; and although this arrangement cannot be made to suit every detail, it pos- sesses all the qualities that can be obtained without employing a very elaborate and much divided grouping of the specimens. In commending a scheme of classification based upon four primary divisions of the plant for adoption by the collector and student, we are fully alive to the many difficulties sur- rounding the subject, and are conscious that any outline laid down for the purpose is simply a convenience for arranging and grouping specimens, and useful for purposes of study or generalisation : it is, therefore, not to be considered as an absolutely true expression of all the details. A perplexity of this kind is well known by all writers upon morphological subjects, and it is realised and allowed for by the student generally. The word "plant" is held to include all vegetable growth, from the loftiest and largest tree to the humblest form. The Mode of Growth and Classification of Galls 29 Four main divisions of the plant have been made and used as terms to express the particular part of the plant upon which the gall may be sought. They are root, stem, leaf, and flower. I. The root-galls are those situated upon or within the roots, adventitious, fibrous, tuberous, or the taproot, or the rhizomes. II. The stem-galls are those situated upon or within the main stem (erect or climbing), the branches, or the suckers. III. The leaf-galls are those situated upon or within or enclosed by the blade, the petiole, the stipules, the bract, or the scales ; or any of these parts enfolding larvs. IV. The flower-galls are those situated upon or within or enclosed by the calyx, the corolla, the catkin, or the subsequent fruit or seed. The fruit, botanically, is acknowledged as a definite and separate organ of the plant, but its inclusion with the flower is due to a three-fold reason : («) It is a direct outcome of the flower, and appears only when the flower has fulfilled its functions. (b) In each case that it is galled the galling agency is present before it arrives at maturity. (c) There are so few galled fruits that it is not necessary to make a separate division to represent them. It may have been noticed by the reader that no reference has been made to the number of the larvje which inhabit the galls. There is, however, a certain uniformity in this respect with all galls, and although it is not of sufficient importance to form a specific feature in nomenclature, reference is made to it in some descriptions of the galls. For this purpose the terms " unilarval " and " multilarval " are employed to indicate whether the gall normally contains one larva or two or more larvs. In the case of the aphides, in which there is no larval condition, the term " multinymphal " is used. These terms arc applicable to the rolled and thickened leaves more than to other kinds. The modes of pupation and the spots selected for it by those species which pass through a quiescent stage are noted in the synoptical descriptions, to enable the student to know under which conditions to keep living examples of galls. 30 British Vegetable Galls Unilarval. Normally one larva only living within a catkin, cluster of leaves, or rolled and thickened leaf-margin — e.g. Cecidoinyia betida, C. rosaria, C. taxi, Lipara lucens, C. pteridis, C. ranunculi. MULTILARVAL. Normally two or more larvae living within a catkin, cluster of leaves, rolled, thickened, or conduplicated leaf, the flower or fruit, and the stem— ^.^. Cecidoinyia cratcegi, C. lathyri, C. veronicce, C. violce, C. marginemtor- quens, C. persicaricB, C. rosaruin, Lasioptera rubi. MULTINYMPHAL. E.g. Pemphigus bursarius, P. spirotheccc, Tetraneura ulmi. CHAPTER VI. The Agents concerned in the Production of Galls. Five different orders of insects and two classes of worm-like creatures are the principal producers of galls. Several species of fungi added to these complete the list of all the agents at present known as operating upon British plants for this purpose. They are as follows : — I. Acarina, or Mites. II. Anguillula, or Eclworms. III. Colcoptcra, or Beetles. IV. Diptera, or Flies (with two wings). ^ V. Fungi, or Fungus. VI. Hemiptera-Homoptera, or Aphides. VII. Heterocera, or Moths. VIII. Hymenoptera, or Wasps (small). It has been found more convenient to place them in alpha- betical order, rather than according to the natural order which they severally occupy in the animal kingdom, or in relation to the numerical preponderance of the species embraced in each class. I. The Acarina, or Mites. These creatures are chiefly remarkable for their exceedingly diminutive size. Andrew Murray, F.L.S., appears to have been the first in this country to collate the information concerning the mites in general. He isolated those which cause deformities on plants, and placed above them the name of Gall-mites, classing them as the sub-family Phytoptid^ ; and in his "Economic Entomology" he gives a most excellent account of their habits, etc. 31 32 British Vegetable Galls Within the last few years elaborate researches have been made into the economy of these creatures by Dr. Alfred Nalepa, of Vienna. To his writings all gallists are indebted for a more extended knowledge of gall-mites. He has determined and named 227 Continental species, and is familiar with about twenty others ; some thirty of these are at present known in Britain, and doubtless dozens more will in time be discovered. He has established various genera, families, and sub-families, the gall-producers among them being Eriophyinse, Phyllocoptinje, and seven others. These creatures vary in size from 250 /i long, 60 /x broad in thee?, and 310 /x long, 60 fi broad in the ?, of Eriophyes mentJiarins, which is the largest known species, to 90 /x long, 30 /i broad in the c?, and 100 /a long, 37 /i broad in the ? of E. pai-vulus, a difference in the c?c? of 160 /it long. 30 /u. broad, and in the ? ? of 190 /x long, 23 /i broad. The largest species is scarcely visible to the keenest naked eye. The entire creature is long and cylindrical, of a vermiform shape, the head being fused to the thorax, and that in turn to the abdomen. The head and thorax are hidden from above by a hemi- spherical, shield-like plate, bearing upon it characteristic sculptural markings, which form important features in the nomenclature. The head is slightly bent in a downward direction, and is pointed, or snouted. The mandibles are needle-shaped. The maxillae are three-jointed, and are used as antennae. The abdomen is greatly elongated, diminishing in size towards the tail ; it is ringed all round. The number of the rings varies from 40 in E. gotiiothomx to 95 in E. buxi. Several (generally seven) pairs of long, stiff bristles, or setiv, are always present on the body, and they appear to serve the purposes of organs of touch. The tail is divided into two semi-circular flaps, which can be closed together at will and withdrawn ; it bears at its extremity one pair of whip-like bristles much longer than the other pairs. The anal opening is close to the flaps. The generative organs are partially external, situated on the ventral surface of the abdomen, close to its union with the thorax ; they are known as epiandrhwi for the $, epigynium for the ? . The mites have no special respiratory or circulatory organs. The exchange of gases takes place through the body. Nor is there any organ like a heart ; the fluid, therefore, which is The Agents concerned in the Production of Galls 33 analogous to blood moves freely and irregularly throughout the body. The nerves are in four pairs. The cesophagus passes through the brain ganglia. They are devoid of stomach, digestion taking place in the larger intestine. Salivary glands are wanting, and also Malphigian tubules. The skin is an exceedingly thin, colourless layer of chitin. Beneath it lies a network of branched cells which contain slight colouring pigments. The legs are four in number, all exactly the same size and shape ; they are five-jointed, situated close to the head, and always point forward. A very few small bristles are upon them. Mostly they are furnished with a small claw, but some have a knob instead. The tarsi have a number of fine bristles arranged upon them, producing a feathered appearance. The colours are pure white, yellowish white, orange-yellow, and brownish yellow when old. The ? lays great numbers of eggs, the membrane of which is composed of chitin. In shape they are round, elliptical, or ovid. When deposited late in the year they do not hatch in the following spring, their vitality being destroyed by frost ; those deposited in spring and summer hatch quickly. From them emerge larvse very similar in appearance to the parents, and can be distinguished only by slighter size, a less number of sitce, and absence of sexual organs exteriorly. Ecdysis occurs twice at least during the larval stage, the sex not being manifest until after the second. The nymphal stage is characterised by the progress of development, and a slight protrusion of the sexual organs. The imagines spend the winter on plants — by preference in the buds — and in the ground. Some species exude a flocculent substance from portions of the back. They are very sensitive to the action of light upon their bodies, and evade the sunlight which kills them. They do not all make galls ; some live as parasites and inquilines upon those which do. Their two chief enemies are gamasides, which attack them when away from the galls, and a fungus (sp. ?), the hyphse of which penetrate the body and cause death. The foregoing notes are derived mainly from Dr. Nalepa's publications. 3 34 British Vegetable Galls II. The Angullula, or Eel-worms. The minute nematoid worms popularly known as Eel-worms are very destructive to many kinds of plants, more especially cereals. Their name is indicative of their shape which under magnification is seen to bear a very close resemblance to an eel. They are very small, thin-skinned, and live in enormous numbers. About six species produce galls. The ova of these creatures are relatively large ; the larvas quickly develop from them, and at once commence to suck the sap from young roots and to bore into them. When fully grown they are not quite i mm. long. They attack the roots and other parts of wheat, rye, oats, clover, parsnips, beet, lettuces, tomatoes, cucumbers, and peach-, pear-, and walnut- trees. Several wild plants are also affected, Poa annua, Achillea viillifolium, and Polygonum persicaria amongst them. The mouth is furnished with an exertile, sharply pointed spine, which is employed to penetrate the tissues of the plants. They bore into and live within the plant, producing galled growths, and considerably retard its development. The generations succeed each other very rapidly. About thirty days only is necessar)- from the emersion of the embryo from the egg to the mature se.xual adult form. Kuhn's investigations have supplied many details concerning the species Heterodera scluiclitii, which affects the beetroot. The ? may be found attached to the rootlets of the beet. At a certain stage of growth she becomes distended into the shape of a lemon, which causes her death. The skin is then a mere sac, which may contain as many as 400 ova. The larvae emerge from the majority of these within the sac, but, owing to the pressure from within, it ultimately ruptures, and the larvae are liberated ; they at once commence to attack the rootlets around them, and cause the formation of gall-growths. III. The Coleoptera, or Beetles. The galls caused by beetles are known as Coleopterous Galls. It is very remarkable that among all the British beetles, which number about 3,300 species, only about fourteen cause gall- formations in the plants upon which the larva; feed. Probably The Agents concerned in the Production of Galls 35 there are more, which will become known as the knowledge in this department of natural history increases. The beetles deposit their ova in various parts of the plants, including the roots, stem, flower-head, and seed-cases. They are mostly unilocular galls, and are not of any very great size. The family of the Weevils embraces almost all the gall- makers, and in point of size the imagines themselves are not large. Saperda poptdiiea is the largest and the principal species. IV. The Diptera, or Flies (with Two Wings). The order of Diptera is represented amongst the gall-making creatures by about 105 species. They are usually spoken of as Gall-gnats and Gall-midgcs. The most renowned of them all is the formidable and dreaded yet diminutive insect, the Hessian fly {Cecidoinyia destructor Say.). So much has been written about this destructive fly that we forbear to add any further remarks concerning it. The sub-genus of Cecidomyia Lw. embraces the largest number and the smallest in size of the British Diptera, and also several species whose natural life is numbered by a few hours only. The sub-genus Diplosis Lw. contains about twelve gall-making gnats, the most interesting species being Diplosis tritici Kirby (the wheat-niidge). The sub-genus Hormomyia Lw. contains about ten species. The larvae of Hormomyia piligera Lw. produce one of the prettiest of the small galls. The remaining sub-genera and families (for which see Tables at end of volume) embrace fifteen other species. The largest of the gall-making Diptera is Lasioptera riibi. The gall-gnats have very small bodies, with relatively long and broad wings, which are narrowed at the point of attachment to the thorax and rounded at the distal end ; they are generally covered on both surfaces with exceedingly fine hairs. The anterior margin of the fore wing is edged with hairs ; the posterior margin having attached to it a number of small scales, similar in shape and appearance to lepidopterous scales. Owing to the presence of hairs, the wings are highly iridescent A large number of the hairs, and almost all the scales, are lost after the fly has been on the wing for some time. 36 British Vegetable Galls They are possessed of two large and well-developed eyes. Ocelli are present in but few species. The antennae are composed of numbers of spherical or cylindrical joints, which in several species of Cecidoinyia number 22 to 24 ; they are moniliform in character. From each joint proceeds a number of long, slender, spreading hairs. The legs are very long and slender. The abdomen is cylindrical, and in the ? terminates with a long, pointed ovipositor, which projects considerably. The $ $ are usually smaller than the ? ? . The colours of the gall-gnats are usually very bright, yellow, orange-yellow, or red being the most usual, all of which, un- fortunately, fade at death. V. Fungi, or Fungus. Of the known species none is excessively destructive as regards its ravages upon the foods of man. The fruits mostly affected are the various varieties oiPrunus. Occasionally quantities of plums are affected, resulting in a loss to the fruit-grower. Exoascus institia Kerner, is the cause of the peculiar distension of the fruit Some fine examples of the manner in which bullaces are rendered unfit for use will be seen on plates 126 and 129. Anton Kerner (" Nat. Hist. Plants," ii. 526) proposes the term " Myco-cecedium for a gall that owes its origin to the attacks of fungus." It appears to be very suitable for such. It has recently been stated by M. Noel Bernard, a French botanist, that the potato is the result of the growth of the fungus Fusarium solani: " M. Bernard took sixteen tubercles of the variety called in France ' Marjohn,' and planted them in flower-pots filled with fine silicious sand. Eight flower-pots were put aside under a glass frame. The other eight pots, in the soil of which a few chips of potato had been sown bearing Fusm-iiiin fungus, were placed in another frame-house. Every one of the latter lot brought forth potatoes after a couple of months, while the eight flower-pots of the first lot were found to contain long, slender roots. . . . It is suggested that early potatoes might be obtained by sowing the soil with cultures of Fusarium solani." — Daily News, March i6th, 1901. The Agents concerned in the Production of Galls 37 VI. The Hemiptera-Homoptera, or Aphides. The ravages of several species of Aphides, commonly termed Green-fly and Plant-lice, are only too well known by floriculturists, professional and amateur. There are, however, a very large number of species of aphides, all of which live on plants, and very few genera are exempt from their attacks. The life-history of an aphis is exceedingly interesting, but it is too lengthy to be given here. The body is divided into three sections — head, thorax, and abdomen. The most noteworthy organ of the head is the rostrum. It is a long, hollow bag, and contains three exceedingly fine lancets. With them the insect punctures the plant, and sucks the sap through the rostrum. In some species it is short, but in the majority it is long. It projects from the head, and when not in use is recurved beneath the body. The long rostra project beyond the body and produce the appearance of a tail. Some species of aphides have neither eyes nor cornicles, but these features are almost entirely confined to subterranean species. The wings are very large in comparison with the body. When in flight a compound hamulus on the costal margin of the hind wing fastens in a fold of the posterior margin of the fore wing, keeping both in the same plane. The legs are long and thin ; in some species smooth, in others hairy. The chief external feature of the abdomen is a pair of cornicles ; they are of a horny nature, diverse in form and size, upright and mobile, tubular in form, and they act as excretory ducts. The fluid which exudes from them is known as honey- dew. Within the abdomen a substance is secreted in certain glands, from which it exudes in the form of a flocculent sub- stance, often entirely covering the insect. One remarkable feature about aphides is that manyspecies have, in addition to mature winged c?c? and winged ? ?,an alateform. VII. The Heterocera, or Moths. Very few indeed are the species of moths the larv^ of which are known to produce galls. Not half a dozen can be enumerated. At present five only are known. None occur 38 British Vegetable Galls on roots. Two are illustrated in this volume, the descriptions of which will be found on plates 36 and 37. VIII. The Hymenoptera, or Wasps (Small). The insects belonging to the order of Hymenoptera that produce gall are known as Gall-wasps. The imago has four wings. The pair on each side of the thorax are held together, while employed in flight, by means of hooklets, or hamuli. This order includes bees, wasps (social and solitary), ichneumons, and ants, but none of these appears to produce galls. It is among the family of Cynipidce that the gall-pro- ducing hymenoptera are found. The bodies of these insects are of very beautiful and bright metallic colours. Red, green, orange, and blue colours pre- dominate. The wings also are exceptionally iridescent. Gall-wasps are very agile and graceful in their movements. The ? ? possess an instrument of very fine and delicate construction known as a seta, or tercbra, which is used for the purpose of oviposition. The terebra is very long, and can be made to pene- trate deeply into the vegetable tissues, or between the scales of a leaf-bud. Each ovum when deposited in a mass of tissue has an elongated appendage known as the eggstalk, the end of which is very near the surface of the plant. From its arrangements and its contents, it has been considered an organ of respiration to convey oxygen to the embryo deep down in the tissues. The phenomena of parthenogenesis and alternation of generations are the most wonderful features connected with the Cynipidce. These subjects can be more suitably treated in a contemplated volume on the oak-galls, than here. The larva; are apodus, white, and fleshy ; they move very little. The length of time required for development is very variable. The pupa; are white, and all the limbs and the wings can be clearly seen through the puparium. The imagines are peculiar, not only in the manner of oviposition, but in taking no food, and in not frequenting flowers ; they also feign death. All the galls they produce are completely closed, and are of two kinds, soft and succulent, or hard and woody. Some species of the CynipidcE disregard the cold of winter and lay their eggs during very unfavourable weather. THE ROOT^GALLS. The Root-galls are those situated upon or within the Roots (Adventitious, Fibrous, Tuberous), or the Tap-root, or the Rhizomes. Galls caused by the larvae of Ceuthorhynchus sulcicoUis Gyll. the root of Brassica napus Linn. PLATE s. Synonymy of Insect. Ceuthorhynclius phnrostigma Marsh. sulcicollis Payk. Habitat of the Common Turnit. — It may be obtained from the fields of almost every farm or any greengrocer's shop throughout the country. The Gall is formed by the irritation to the tissues caused by the feeding of the larva. Position. — On the subterranean portion of the root, but seldom on the tap-root. Manner of Growth.— Generally gregarious ; glabrous. Colour. — Same as the root itself. Average Dimensions of a Mature Specimen. Height, 13 mm. ; girth, 50 mm. May be sought during the months of September, October and November. The Growth is complete by the end of October. The Typical Condition of the gall is unilocular and unilarval. The Larva pupates in the ground. The imago emerges during the spring. The gall is also figured by Miss Ormerod, " Injurious Insects," p. 35 ; " The Roj-al Natural History," section xi., p. 151. 41 42 British Vegetable Galls The ravages of this species in the bulbous portion of the root of the common turnip and also that of the swede turnip are sometimes very considerable. They do not, however, greatly diminish the value of the turnips ; but sometimes the rapid decay of a root is due to moisture getting in the cavities after the larvae have vacated them. The tap-root is not often galled, although the root-fibres are frequently caused to swell to enor- mous proportions (see plate lo). The gall-growths assume the shape of mammillatcd protuberances or warty excrescences. They are variable in number, some roots having but very few, others as many as forty. They are mostly separate from each other ; occasionally, however, several will coalesce, especially when there are many galls on a root. The author has seen an example in which fifteen had coalesced. The specimen in the illustration measured 9J in. in girth immediately beneath the row of galls; iii in. over the top of them ; and 13^ in. in girth in its vertical circumference. The tap-root was i^ in. long. It had upon it twenty-three well- defined larval chambers, ten of which can be seen. The larva is apodus, and lies in the cavity it makes by feeding on the gall-substance, with head and tail close together, after the manner of a Cynips larva. When fully fed it eats a way out and pupates in the earth, particles of which it uses in the formation of the cocoon. The specimen illustrated was taken out of a field near Hastings by the author. Plate 8. K.OOT OF Bi-assicn mipiis Linn. Ceiithorhynchiis sulcicollis Clyll. Ceuthorhynchus sulcicollis Gyll. PLATE 9. Galls caused by the larvcc of Ceuthorhynchus sulcicoUis Gyll. the root of the Common Swedish Turnip, Brassica rutabaga De C. PLATE 9. This specimen furnishes a typical illustration of a galled swede turnip. It is also interesting because of the symmetrical arrangement of the galls around the base of the root. It still further shows that the ova are always deposited on or in the subterranean portion of the root, and not on any part which is above ground. The lower third only of this root was below ground. The root has around it seventeen larval chambers. None have coalesced. The illustration, which is half natural size, is of a specimen taken out of a field near Hastings by the author. For details connected with this species, see pp. 41 and 42. Plate 9. Root ok Bmssiia i-ii/a/'agii/iiea Linn. Saperda populnea Linn. PLATE 23. Galls caused by the larvae of Saperda populnea Linn. on the stems of Salix oaprea Linn. PLATE 22. Synonymy of Insect. Habitat of the Sallow, or Goat-willow. — Very common throughout Britain, by the sides of streams, in marshy places, damp open woods, and in thickets and hedges. The Gall is formed by the presence of the larva in the pith causing the surrounding tissues to swell and bulge outwards. Position. — On the stem, branches, and sometimes the twigs also. Manner of Growth.— Singly ; seldom coalesced. Colour. — Same as unaffected part of stem. Average Dimensions of a Mature Specimen. Girth, 66 mm. May be sought during any month of the year. The Growth is complete by the end of September. The Typical Condition of the gall is unilocular. The Larva pupates in the gall. The imago emerges during May. The appearance of these galls is somewhat different from those on the aspen caused by the same species of beetle. In the case of the aspen the puncture made by the ? for oviposition results in a scar being formed, but with the willow this does not appear to be the case. The growth of the willow is more rapid. The epidermis does not close over the puncture, and, as the growth of the stem proceeds, a depression is formed. In the lower left-hand corner of the illustration an imago will be seen. It emerged from the hole above it, a short while before the photograph was taken. The illustration is of specimens gathered at Hastings by the author. 74 ♦( ■^ Stems of .S(i//.\- caprea Linn. Saperda populnca Linn. Agromyza schineri Gir. PLATE 23. Galls caused by the larvae of Agromyza schineri Gir. on the twigs of Salix cinerea Linn. PLATE 23. Synonymy of Insect. Habitat of the Grey Willow.— Common throughout Britain, by the sides of streams, in marshy places, damp open woods, and in thiclcets and hedges. The Gall is formed by the presence of the larva in the cambium layer causing it to swell and bulge outwards. Position. — On the side of the twig. Manner of Growth.— Gregarious ; coalescent ; glabrous ; slightly glossy. Colour. — Green, with wavy longitudinal lines of paler colour. Average Dimensions of a Mature Specimen. Length, 15 mm. ; breadth, 5 mm. May be sought during any month of the year. The Growth is complete by the end of September. The Typical Condition of the gall is unilocular and unilarval. The Larva pupates in the ground. The imago emerges during spring. These galls occur sometimes singly, but generally from two to fifteen on a stem, and are mostly found on young bushes of Salix cinerea. They are oval-shaped, cushion-like swellings which, rising from within the stem, cause the epidermis to crack into longitudinal wavy strands, the edges of which reflect light, imparting to them a whitish colour. This disappears when they are viewed through a lens. Under the same con- ditions small scars may be seen which indicate the holes made for oviposition by the parent fly. The illustration is of specimens gathered at Hastings by the author. 76 Shoots of .SV?//.v ciuena Linn. Agromyza schineri Gir (SIX SEVENTHS NAT. SIZE.) Agromyza schineri Gir. PLATE 24 PLATE 21 Stems of Salix cinerea Linn. (Five-sixths nat. size.) Galled by Agromyza schineri Gir. The stems on the opposite page illustrate the appearance of these galls in the spring and summer of the year following their formation. During the first summer's growth they were the same size and appearance of those in plate 23, the increase in the growth of the wood causing them to present a less elevated condition. The holes through which the imagines emerged may be distinctly seen in the centre specimen. The illustration is of specimens gathered at Hastings by the Author. Plate 24. Stk.ms of Sa/ix cinerea Linn. Agromyza schiiuri Gir. Cecidomyia galii Wtz. PLATE 25. Galls caused by the larvae of Cecidomyia galii Wtz. the stalks of Galium Yerum Linn. PLATE 25. Synonymy of Insect. Cecidomyia mollnginis L\v. „ galii Theobald. Habitat of the Ladies' Bedstraw. — Very generally dis- tributed throughout Britain, growing on banks and pastures, preferably in a fairly dry situation. The G.vll is formed by an enormous accumulation of sap, resulting from the irritation to the tissues and the presence of the larvas. Position. — On the stems and flower-stalks. Manner of Growth.— Singly and gregarious; glabrous, glossy. Colour. — Yellowish white and very pale green. Average Dimensions of a Mature Specimen (globular form). Girth, 30 mm. May be sought during the months of June, July, August. The Growth is complete by the end of July. The Typical Condition of the gall is plurilocular. Usual number of cells, 6. The Larv.e pupate in the ground. The imagines emerge during the spring. These galls attain an enormous size as compared with the slender stems which support them, the diameter of some being twelve times that of the stem. They are very conspicuous. They do not occur in the Hastings district. The author is indebted to the kindness of the undermentioned lady for the specimens of the illustration. From her communications to him it appears that she found the plant to be very local, and the galled stems comparatively few in number. The illustration is of specimens gathered at Mundesley, Norfolk, by Miss Ethel Sayer. Plate 25. Stems of Galium vcniin Linn. Cecidomyia galii Wtz. Cecidomyia saliciperda Duf. PLATE 26. Galls caused by the larv^ of Cecidomyia saliciperda Duf. on twigs of Salix Caprea Linn. PLATE 26. Synonymy of Insect. Cecidomyia terebrans Lw. „ saliciperda Theobald. albipennis Lw., VVtz., Walker. Rhabdophaga vitninalis West. Habitat of the Sallow, or Goat-willow.— Very common throughout Britain, by the sides of streams, in marshy places, damp open woods, and in thickets and hedges. The Gall is formed by the larvas feeding within the stem, causing it to swell, and the bark to crack and burst through the epidermis. Position. — On the twigs, usually at or near the top. Manner of Growth. — Singly or in numbers, separately or coalescent ; scabious. Colour.— Dark green suffused with red ; light brown. Average Dimensions of a Mature Specimen. Length, 20 mm. ; girth, 36 mm. May be sought during any month in the year. The Growth is complete by the end of September. The Typical Condition of the gall is plurilocular. Usual number of cells, 6. The LarV/E pupate in the gall. The imagines emerge during the spring. It is not difficult to find these galls. During the winter is the best time to seek them, the absence of foliage allowing them to be easily detected. They are very irregular in their mode of growth. There may be only one small swelling on a twig, or as many as eight distinct or coalesced swellings within a distance of four inches. Leaf-buds appear on the surface at various points, which, when developed, may have a galled swelling on the petiole. The illustration is of specimens gathered at Hastings by the author. 82 Plate 26. Ci/K 'J'wiGS CK Sti/ix Caprca Linr Cecidomyia saliciperda Duf. Cecidomyia saliciperda Duf. PLATE 27. Galls caused by the larvae of Cecidomyia saliciperda Duf. on the twigs of Salix Caprea Linn. PLATE 27. The illustration on the opposite page gives the appearance of the galls without foliage as seen during the months of December to June, and may be considered as the winter-spring form of these gall-growths. Dimensions of the Specimens. Vertical axis. Horizontal axis. Greatest girth. Fig. A. . .48 mm. 25 mm. 74 mm. Fig. B. . .65 mm. 22 mm. 71 mm. Fig. C. . .72 mm. 21 mm. 63 mm. These may be regarded as very fine examples. The illustration is of specimens gathered at Hastings by the author's sons. Pr.ATp; 27. Twigs oi' Su/ix Caprea Lini Cecidomyia saliciperda Duf. To face page 84. Cecidomyia salicis Schrk. PLATE 28. Galls caused by the larvae of Cecidomyia salicis Schrk. on the twigs of Salix cinerea Linn. PLATE 28. Synonymy of Insect. Cecidomyia salicina Bouche. „ gallanun-salicis. „ Degeeri Bremi. „ argyrosticta Macq. Habitat of the Grey Sallow. — Common throughout Britain, by the sides of streams, in marshy places, damp open woods, and in thickets and hedges. The Gall is formed by the larvs feeding upon the pith and causing the woody cells which surround it to swell. Position. — On the top twigs of the tree. Manner of Growth. — Separately, seldom more than one on a twig ; glabrous. Colour. — Same as the twig upon which it is found. Average Dimensions of a Mature Specimen. Length, 20 mm. ; girth, 36 mm. May be sought during any month in the year. The Growth is complete by the end of October. The Typical Condition of the gall is plurilocular. Usual number of cells, 20. The Larv^ pupate in the gall. The imagines emerge during May. The peculiar lemon-like shape of these galls distinguishes them very readily from other willow-galls. They occur also on Salix aurita. The larvae live in the centre of the swelling, feeding on the pith ; the number in a gall varies from two or three to thirty. The larval chambers are irregu- larly elongated, and have very thin walls. When fully fed the larvjE work their way towards the exterior of the gall, and upon emersion of the imago about half of the puparium is left projecting from the hole. The illustration is of specimens gathered at Hastings by the author. Plate 28. Twigs of Sti/ix cinerca Lii Cecidomyia salicis Schrk. (nearly NAT. SIZE.) Cecidomyia sisymbrii Schrk. PLATE 29. Galls caused by the larvae of Cecidomyia sisymbrii Schrk. on the stalks of Sisymbrium officinale Scop. PLATE 29. Synonymy of Insect. Cecidomyia barbai-ea Curtis. „ sisymbrii Theobald. Habitat of the Hedge-mustard.— This plant grows to the height of from i8 in. to 30 in. in hedges and by road- sides, but less when in waste places and open situations. Abundant throughout Britain. The Gall is formed by the larvze causing a cessation of upward growth and a consequent crowding together of flowers and seed-pods. Position.— At the termination of the shoots. Manner of Gro\vth. — Singly ; glabrous. Colour. — Slightly paler green than other portions of the plant. Average Dimensions of a Mature Specimen. Height, 15 mm.; girth, 30 mm. May be sought during the months of June, July, and August. The Growth is complete by the end of July. The Typical Condition of the gall is multilarval. The Larv^ pupate in the gall. The imagines emerge during the autumn. It is not improbable that the imagines which emerge during the months of September to November oviposit in some other plants, and that the larvae therefrom remain in the galls they then cause until the following June. The illustration is of specimens gathered at Guestling, near Hastings, by the author. 88 Plate 29. Shoui.s ok Sisyinhriiiin otjicinalt: Scop, Cccidonivia sisMiibrii Schrk. Cecidomyia tille Schrk. PLATE SO. Galls caused by the larvae of Cecidomyia tiliae Schrk. on the twigs of Tilia grandifolla Ehrh. PLATE SO. Synonymy of Insect. Cecidoviyia limbivolens Macq. „ excavans Macq. „ tilicB Theobald. Habitat of Tilia Grandifolia.— This tree occurs through- out Britain in woods, parks, avenues, etc. It is profuse in its foliage and flowers, and assumes handsome and noble proportions. The Gall is formed by the ova being deposited in a bud ; the larva, when hatched, feed upon the interior and prevent development. Position. ^At the axils of young twigs, and sometimes on the petiole. Manner of Growth. — Sessile ; glabrous ; more or less globular. Colour. — Green, greenish yellow, orange-yellow, bright red. Average Dimensions of a Mature Specimen. Length, lo mm.; Girth, 15 mm. May be sought during the months of June to October. The Growth is complete by the end of July. The Typical Condition of the gall is plurilocular. Usual number of cells, 20. The Larv.e pupate in the gall. The imagines emerge during August. On young shoots which grow around the stumps of lime- trees, these galls may also be found. They are somewhat variable in shape, mostly quite globular ; others, however, are oblong, and occasionally specimens are to be found spindle- shaped. Their bright colouring causes them to be very notice- able against the beautiful green of the leaves of the tree. It is remarkable what a large number of larval cells are enclosed within a specimen of average size. The illustration is of specimens gathered at Aylsham, Norfolk, by the author. 90 Plate 30. Twics OF Tilia t'TiUiJifii/id Eh Ceciiiomyia tiliir Schrk. Galls caused by the larvae of Lasioptera rubi Schrk, on the stems of Rubus fruticosus Linn. PLATE SI. Synonymy of Insect. Lasioptera picta Mg. „ argyrosticta Mg. „ fusca Vallot. „ rubi Theobald. Habitat of the Common Bramble.— Very plentiful in every part of Britain in waste places, woods, disused country roads, hedges, coppices, etc., asserting itself in every way. The Gall is formed by the swelling of the pith and medullary tissue. POSITION.-On the sides of the b.amble-shoots. Manner of GROWTH.-Singly ; sometimes close together rarely coalesced. COLOUR.-Dark green at first ; brown or reddish brown when mature. Average Dimensions of a Mature Specimen. Length, i8 mm. ; girth, 36 mm. May be SOUGHT during any month in the year. The Growth is complete by the end of September. The Typical Condition of the gall is multilarval. The Larv^ pupate in the gall. The imagines emerge durmg May. When these galls are required as specimens for iUu.stration or mountmg m a case they should be gathered in September or October ; for the purpose of rearing the inhabitants, however they must be allowed to remain in situ until March or April but not later. See also plate 117. ' The gall is also figured in "The Royal Natural History" sect. XI., p. 20. ■* ' Lasioptera rubi. The size of these galls is very variable. From that of a mere swelling they attain dimensions the girth of which is often six or more times that of the stem upon which they are growing The length of the swelling which they cause seldom exceeds i^ in. The gall-growth usually takes place on the side of the stem, but specimens are occasionally met with where it is evenly distributed all round the stem. Sometimes the parent fly deposits her ova where a small shoot branches off the main stem, a bulbous growth is then the result ; at another time the termination of a shoot is chosen. The interior of the gall shows an irregular-shaped cavity containing from four to seven larvae surrounded by fras. These galls are neither easy to find nor to procure, and being usually in the midst of bramble-bushes, where the growth of shrubs and trees is thickest, the search for them is often attended with many scratches. The illustration on the opposite page is of specimens gathered at Hastings by the author. Fig. 1. A Fine Specimen. A. As growing. B. Section. To face page 92. Plate 31 Stems ok A'/ih/s fruticonis Linn. LasiophTii rubi Schrk. LiPARA LUCENS Mg. PLATE S2. Galls caused by the larvae of Lipara lucens Mg. the stem of Arundo Phragmites Ben. PLATE 32. Synonymy of Insect. Habitat of the Common Reed.— Common in Britain in marshes, streams, shallow pools, ditches by railway em- bankments, and lakes in private parks. The Gall is formed by the leaves overlapping and enfolding one another, this being caused by the larva preventing the upward growth of the stem. Position.— At the top of the stem. Manner of Growth.— Singly ; glabrous, glossy ; torpedo- shaped. Colour. — Yellowish green. Average Dimensions of a Mature Specimen. Length, 70 mm.; breadth, 10 mm.; girth, 26 mm. May be sought during the months of June, July, August, and September. The Growth is complete by the end of August. The Typical Condition of the gall is unilarval. The Larva pupates in the gall. These galls are not common. This fact is due mainly to the cutting down of the reeds in many parts of the country during September for thatching purposes. They are often very difficult to obtain, unless the gallist can go amongst the reeds in a boat, or search the stems after they have been thrown on the bank by the mower. In the illustration will be seen, on the right side of the centre galled stem, a panicle, and on the left side an unaffected stem. The galled stems never produce panicles. The illustration is of specimens gathered in Ashburnham Park, Battle, by the author. Plate 32. -Ml OK Anotdo P/irtii^iiiltfS Bt-ntham. Lipiini luccns Mg. Galls caused by the larvae of Urophora cardui Linn. on the stems of Carduus arvensis Curt. PLATE 33. Synonymy of Insect. Trypeta cardui Linn. „ Walker. Habitat of the Creeping Thistle. — Grows in fields, on hill-sides, waste places, semi-cultivated places, etc., in sheltered and exposed situations abundantly all over Britain. Position. — At the top of the stem and also at the nodes. Manner of Growth.— Singly ; glabrous, glossy. Colour. — Pale green, becoming darker with age. Average Dimensions of a Mature Specimen. Height, 24 mm. ; girth, 70 mm. May be sought during the months of July, August, September. The Growth is complete by the end of August. The Typical Condition of the gall is plurilocular. Usual number of cells, 4. The Larv/E pupate in the gall. The imagines emerge during May and June. The operations of the larvas of this species are in keeping with those of Uropltora solstitialis. They develop from the ova simultaneously with the unfolding of the apical portion of the thistle, when it is about to produce the flowers, and arrest its further upward growth. The ascending sap accumu- lates and gives rise to a large bulbous swelling, which the larvae eat into in a downward direction. The apertures of the galleries remain open, the fras, however, being allowed to remain in them. 95 Urophora cardui. This conspicuous and unmistakable gall may often be seen on the thistles growing on a patch of waste ground. The galls occur at the summit of the plant and also at the nodes, and in almost every instance prevent a continuation of growth. In the early stages of development it is very soft and sappy, the outer layer more so than the interior. It, however, soon becomes more solid, and continues to harden until it is of a woody nature. At first it is a delicate pale green ; this with age changes to a dark green, and ultimately, in unison with the rest of the plant, turns brown. Leaves spring in all directions from the surface of the gall, and at the top form a tuft, imparting a graceful and attractive appearance. Such a specimen may be seen in the lower corner on the right-hand side of plate 33. The larvae are usually four in number, each occupying a separate gallery. They eat from above downwards, increasing the size of the gallery as they descend. The illustration is of specimens gathered at Hastings by the author. • A. The imago, x 5. Plate 33. Stems ok Carditiis arvensis Curt. Urophora cardiii Linn. Galls caused by the larvce of Adelges abietis Linn. on the twigs of Abies excelsa De C. PLATE 34. Synonymy of Insect. Clurmes abietis Linn., Fab., Schr., Kalt., Pass., Kerner, Koch, Ormerod, Ratz., Leuchart. Adelges gallaruin abietis Haliday. „ abietis Walk. Sacchipliantes abietis " Ruricola." Habitat of the Spruce-fir.— Indigenous in the Scottish highlands. Planted all over Britain in parks, enclosures, private grounds, and nursery gardens. The Gall is formed by the accumulation of sap around punctures made by the queen aphis at the axils of the young leaves, causing their bases to thicken. Position. — At or near the end of a twig. Manner of Growth.— The larval chambers are gregarious, imbricated, and sessile. Colour. — At first pale green, darker later, ultimately chocolate- brown. Average Dimensions of a Mature Specimen. .Length, 40 mm. ; breadth, 16 mm. ; girth, 36 mm. May be sought during the months of April, May, June, Jul>-. The Growth is complete by the end of June. The Typical Condition of the gall is plurilocular. Usual number of cells, 25. ECDYSIS takes place in the gall. The imagines emerge during June. The popular name of pine-apple gall is very appropriate. Before the scales separate to allow the pupa; to emerge, it bears a very close resemblance to a pine-apple. In their dried condition they may be observed on Christmas-trees used at children's parties. The gall is also figured by Miss Ormerod, " Injurious Insects," 1890, p. 267; Buckton, "British Aphides," vol. iv., plate 116; "The Royal Natural History," sect, xi., p. 199; A. Kerner, " Nat. Hist, of Plants," vol. ii., p. 534. 97 7 Adelges abietis. If the twigs of a spruce-fir, or Christmas-tree, be carefully examined during the month of April, the chances are very- many that the foundress of the colony of aphides, which three or four months later will be swarming on the same twigs, may be seen occupied in depositing ova and in puncturing the axils of the young expanding leaves. The queen, or foundress, has hybernated during the winter, and upon the return of mild weather and ascending sap, emerges a thin and wingless shrivelled creature. By absorbing the sap her condition is speedily changed to that of rotundity. At the conclusion of oviposition she dies. The punctures made by her rostrum at the axils of the young leaves cause a diversion of the sap, and the bases of the needle-like leaves thicken and swell, forming numerous cavities of which the larva; take possession. The twig attacked forms an axis, around which the larval chambers are arranged, each containing about thirty-five larvae. The larvae, by the constant punctures made with their rostra to suck the sap, cause the continual development of the growth. During May they assume the pupal stage. Towards the end of June they make their way through the gaping apertures of the scales, crawl up the needles, emerge from the puparium as imagines, and in twenty minutes or less can fly away. One of these conglomerations of larval chambers may contain from i,8oo to 2,000 insects. At the close of the summer these false cones, as they are termed, dry, turn black, and several years will elapse before disintegration is complete. The illustration is of specimens gathered at Hastings by the author. Plate 34. ittl.o ul Al'us HAicha I)c C. Adelines a/'ietis Linn. To face page 98. Galls caused by the queen and nymphs of Schizoneura lanigera Haus. ou a branch of Pyrus Malus Linn. PLATE So. Synonymy of Insect. Aphis lanigera Haus., Ger., Kirby and Spence. Eriosoma viali Leach, Mosley, Haliday. „ lanigera Fitch. Schizoneura la?iigera Htg., Kalt., Pass. Myzoxylus niali Blot., Tong., Amyot. Habitat of the Apple-tree.— Grows in orchards and gardens throughout the length and breadth of the country. The Gai.l is formed by the exudation of sap resulting from the continuous punctures of the rostra of the aphides. Position.— On the trunk, branches, and twigs. Manner of Growth. — Rounded protuberances with rugose surface. Colour.— Brownish, with grey spots and patches. Average Dimensions of a Mature Specimen. Girth, 7 in. May be sought during any month in the year. Particulars of Plate. — Length of bough, 20 in. ; length of lower twig, 5^ in. ; length of centre twig, 7 in. ; length of excrescence on left hand, 4 in. ; girth of unaffected portion of branch, midway between lower twig and centre twig, 90 mm. ; girth of galled portion of branch, midway between lower twig and centre twig, 160 mm. ; girth of excrescence on left hand at greatest circumference, 156 mm. The gall is also figured by Miss Ormerod, " Injurious Insects," 1890, p. 279, "Insects Injurious to Orchard and Bush Fruits," 1898, p. i; and also Buckton, "British Aphides," vol. iii., plate 106. 99 Schizoneura lanigera. In the illustration opposite is shown the all too familiar ' American blight." The swellings are the result of the con- tinuous punctures of the rostra of the aphides, causing thereby an ever-increasing flow of sap, and producing large warty swellings on every part of the trunk and limbs of apple-trees. In old and neglected orchards, more partidularly in the west of England, trees may often be seen with every branch affected in a similar manner to that shown on the opposite page. Various preventions and remedies are now being resorted to, and apple growers are becoming aware of the fact that it can be checked, as well as prevented from spreading. The presence of the aphides upon a tree in the summer time is unmistakably shown by a quantity of white, downy substance on the trunk, branches, and twigs. This is secreted by the aphides, and with it they surround themselves, and are rendered sufficiently buoyant to be carried a long distance by the wind. The injury done to the tree results from the flow of sap through the wounds made by the aphides. Being drawn away from the young shoots, leaves, and fruit, the sap accumulates into soft, pulpy swellings forced up through the bark. During the autumn and winter these growths dry, and as they do so cracks appear on their surface, producing scabby hypertrophies, many of which attain enormous dimensions. Within the crevices ova are deposited and the imagines hybernate. With the return of spring, and a renewal of attacks, the galls increase in size. The illustration is of specimens gathered at Hastings by the author. Plate 35. 1 \M 11 ..1 J'ynis Mains Linr GALLED BY Schizoneura lanigera Haus. Hedya aceriana Dup. PLATE 36. Galls caused by the larvae of Hedya aceriana Dup. on the twigs of Populus alba Linn., var. canescens PLATE 36. Synonymy of Insect. Spilonota aceriana Mann. Habitat of the White Poplar. — In Britain this tree is .seldom found in a wild state. It prefers the edges of streams, ponds, and other damp situations, often forming a striking feature in large gardens and private grounds. The Gall is formed by the swelling of the young shoot as a result of irritation due to the presence of the larva. Position.— At the end of the twig. Manner of Growth.— Singly ; slightly pubescent. Colour.— Silvery white. Average Dimensions of a Mature Specimen. Length, 18 mm. ; girth, 24 mm. May be sought during the months of June, July, and August. The Growth is complete by the end of July. The Typical Condition of the gall is unilocular and uni- larval. The Larva pupates in the gall. The imago emerges during August. The larva eats its way into the young shoot, causing it to bulge considerably. In course of time cracks appear on the surface, disclcsing dark brown decaying tissue within. After the escape of the imago, one crack widens until the interior of the cavity is laid bare. The larva ejects its fras through an opening at the top of the larval chamber, and instead of falling away it is retained, and a bag-like pendant mass is formed on the outside. The illustration is of specimens gathered at Hastings by the author. Plate 36. '\vii;.s OK I'opuliis alba Linn., var. cancsaiis. Hcdya aceriana Dup. (THREE-rOURTllS NAT. SIZE.) Retinia resinella Linn. PLATE 37. Galls caused by the larvae of Retinia resinella Linn. on twigs of Pinus sylvestris Linn. PLATE 37. Synonymy of Insect. Parasite. — Glypta resinana. Habitat of the Scotch, Norway, or Riga Pine-tree. — To be found all over Britain. It is indigenous in the Scotch highlands. The Gall is formed by the larva feeding upon the young shoot and causing an accumulation of resinous sap around it. Position. — At the end of the twig. Manner of Growth.— Singly ; glabrous ; resinous ; somewhat ovid in outline. Colour — Dull grey with darker patches. Average Dimensions of a Mature Specimen. Length, 25 mm.; breadth, 18 mm.; girth, 40 mm. May be sought during the whole of the year. The Growth is complete by the end of the autumn. The Typical Condition of the gall is unilarval. The Larva pupates in the gall. The imago emerges during March. These galls appear to be almost entirely confined to Scotland and the northern counties of England. The ovum is laid among the buds at the extremity of a young shoot, and as soon as the larva hatches it feeds upon and within the stem, causing exudation of sap, which encloses the larva and increases in size until pupation takes place. The gall is also figured in "The Royal Natural History," sect, xi., p. 120. The illustration is of specimens supplied by Mr. F. W. Terry, of South Kensington Natural History Museum. Pi ATE 21 Twigs of Pima sxlvcstris Linn. Relinlii resuiella Galls caused by the larvce of Aulax hieracii Schenck the stems of Hieracium sylvaticum Sm. PLATE SS. Synonymy of Insect. Cynips hieracii Bouche. Aulax sabaudi Htg. „ hieracii Schenck, Mayr, Cameron. „ gj-atninis Cameron, Mayr. Habitat of the Wood Hawkweed.— Grows in open places in woods, on hedge-banks and old walls, also in meadows ; very common throughout Britain. The Galls are mostly ovid or pyriform in shape. Position. — On the roots and the stem usually near the flower- head. Manner of Growth.— Seldom more than one gall on a plant. Colour. — Green, sometimes tinged with red, and very pubescent. Average Dimensions of a Mature Specimen. Length, 25 mm. ; breadth, 17 mm. ; girth, 40 mm. ' May be sought during the months of June, July, and August. The Growth is complete by the end of August. The Typical Condition of the gall is plurilocular. Usual number of cells, 20. The Larv/E pupate in the gall. The imagines emerge during the spring. If one of these galls be cut open during the winter, the larval chamber will be found to contain both larvje and pupje. Parasites. — Torynms hieracii Mayr, T. chlorinus Foer., T. euchloris Bohm., Eurytoma signatus Nees., Systole castani- vctitris Gir., and others. The gall is also figured by Peter Cameron, " British Phyto- phagous Hymenoptera " (Ray Society), vol. iv., plate 9. 105 Aulax hieracii. When situated at the summit of the stem this gall is not conspicuous, being somewhat screened from view by the leaves which cluster around and above it. Some leaves also grow out from its surface. The swellings occur on any part of the stem and on the roots, but the top of the stem is where they arc most frequently seen. Generally they are the same colour as the stem, and, like it, thickly clothed with long, silky, greyish hairs ; but examples may be found where they are suffused with pink or red and very attractive and pretty. The leaves are not affected in shape or size by the presence of the swelling ; they spring from the stem below it and above it, as well as from all parts of its surface. When past maturity the hairs fall off and the surface becomes glabrous, hard, and of a dull brown colour. The growth of the interior, in all its stages, much resembles that of A. hypochcBridis. The larvae and pupa; also are not easily observable until approaching maturity ; when, however, the gall reaches that condition many larval cells will be found within the tissues. The larvse pupate within the cells, remaining there during the winter secure from enemies. In the spring the imagines eat their way out, leaving small circular holes as evidences of their departure. The illustration is of specimens gathered at Hastings by the author. Plate 38. Hicraciiim sylvatimm Sni. Aiihix hieracii Schenck. Galls caused by the larvae of Aulax hypochoeridis Kieffer on the flower-stalks of Hypochoeris radicata Linn. PLATE 39. Synonymy of Insect. Aitlax hypochoeridis Kieffer. „ Itypochceridis Cameron. Habitat of the Cat's-EAR. — This plant may sometimes be found growing profusely on dry spots in disused country roads, also in meadows, around the edges of fields, etc. The Gall is formed by the rapid and enormous multipli- cation of cells in the cellular tissue causing the affected part to distend. Position. — On the main stem, the flower-stalk, and the petioles. Manner of Growth. — Elongated, irregular-shaped swellings ; rugose. Colour. — Pale green ; the same as unaffected parts. Average Dimensions of a Mature Specimen. Length, 35 mm. ; breadth, 10 mm. ; girth, 30 mm. May be sought during the months of July, Augu.st, and September The Growth is complete by the end of August. The Typical Condition of the gall is plurilocular Usual number of cells, 12. The L.\RV^ pupate in the gall. The imagines emerge during the spring. Parasite. — Etaytovta cynipsea Boh. It is remarkable how little the growth of the inflorescence of this plant is affected, even though a gall be immediately beneath it on the stem. The gall is also figured by Peter Cameron, " British Phyto- phagous Hymenoptera " (Ray Society), vol. iv., plate 9. 107 Aulax hypochoeridis. These galls are among those which do not force themselves upon the notice of the gallist, and probably until one knows that the plant is attacked, they are often passed by. The swelling is exactly the same colour as that of the unswollen portion of the plant, and generally occurs low down the stem near the ground, so that it is somewhat hidden among the other stalks springing from the same root. They vary much in size. Seldom occupying less than 15 mm. of the length of the stem and 12 mm. in girth, they attain 85 mm. in length and 45 mm. at greatest girth. The surface is furrowed longitudinally, the ridges of which are continuations of those on the other portions of the stem. The swelling takes place in the pith, in which is embedded from five to fifty larval chambers. It is very succulent, and quickly shrivels when deprived of moisture. Until ap- proaching maturity the larval chambers are not apparent, and many large galls, which to all appearances arc well stocked witli larvae or pupae, may be cut open, and they will not be discovered until the pith is subjected to magnification. It appears to be very local in its habitat, but at times con- siderable numbers are found on spots where the spread of Hypochivris radicaia has not been interrupted. One such place in a seldom used road through a wood near Hastings has yielded them plentifully for several years in succession, and apparently the plants will remain undisturbed for a long while to come. The illustration is of specimens gathered at Hastings by the author. Plate 39. Stems of Hypocha-ris radicata Lii: Aulax hypocluvridis Kieffer. Galls caused by the larvae of Diastrophus rubi Htg. on the stems of Rubus fruticosus Linn. PLATE Jfi. Synonymy of Inskct. Andricus Hartigi Marshall. Diastrophus rubi Marshall, Tasch., Mayr, Cameron. Habitat of the Common Bramble.— Very plentiful in every part of Britain on waste places and disused country roads, and in woods, hedges, coppices, etc., asserting itself in every way. The Gall is formed by the enlargement of the larval chambers within the medullary tissues of the bramble. Position.— On any part of stem. Manner of Growth.— Irregular, spindle-shaped swellings. Colour. — Dark green while growing; brownish when past maturity. Average Dimensions of a Mature Specimen. Length, 60 mm. ; breadth, 12 mm. ; girth, 16 mm. May be sought during any month in the year. The Growth is complete by the end of November. The Typical Condition of the gall is plurilocular. Usual number of cells, 80. The Larv.E pupate in the gall. The imagines emerge during the spring. Parasites. — Torymus macrop terns, T. rubi Schen., Eupelvius annulicornis, Decatoma quercicola Foer., Eurytoma abrotani Gir. The gall is also figured by " The Royal Natural History,' sect, xi., p. 20; Peter Cameron, "British Phytophagou; Hymenoptera" (Ray Society), vol. iv., plate 9. 109 Diastrophus rubl. When searching for these galls the hands should be thickly gloved, or painful scratches will be one result. They may often be easily observed on the arch of a long bramble stem rising above its surroundings, but they are more often low down in the bush, or in the middle of a hedge, in a position requiring a patient search and time and perseverance to secure. They are difficult galls from which to rear the imagines and parasites. After the stem is severed from the root, growth ceases, even though placed in water, and the contraction and hardening of the stem prevents the larva; from pupating or the imagines from emerging. It is advisable to search for the galls during January to April inclusive, or to transplant the stem with its roots to one's garden or a large flower-pot. The swellings of the stem are variable in the length they occupy. Although seldom less than i in., they may be found 6 and 7 in. long. The cells being situated on the side of the stem, or completely encircling it, cause growths varying in girth from a few millimetres to 60 mm. The author has a slender stem measuring only 10 mm. in girth which is swollen by the cells to 38 mm. in girth. The colour is greatly subject to the en- vironment of the plant and the situation of the galls upon it. Specimens from the middle of a thick hedge will be much paler than those more exposed to the vagaries of the weather. Some also will be thickly beset with thorns, and others devoid of them. The illustration is of specimens gathered at Hastings and Aylsham by the author. Plate 40. Galls caused by the larvae of Eurytoma hyalipennis on the haulms of Aramophila arundinacea Host. PLATE 41. Synonymy of Insect. Habitat of the Sea Matweed.— This interesting grass is frequent on the British coasts, more especially in Norfolk, Northumberland, and the coast of Sussex to the eastward. The Gall is formed by the irritation caused by the larva, which feeds upon the medullary tissue and prevents further upward growth. Position. — At the top of the haulm ; sometimes obscure amongst the other grass. Manner of Growth. — Solitary. Colour. — At first the leaves are deep pink, which, as growth proceeds, become lighter, ultimately assuming a straw- colour. Average Dimensions of a Mature Specimen. Height, 45 mm.; girth, 21 mm. May be sought during any month in the year. The Growth is complete by the end of October. The Typical Condition of the gall is unilocular and uni- larval. The Larva pupates in the gall. The imago emerges during June. The plant upon which these galls are found is known as the common sea-grass, the sea-reed, the marum, the matweed, and esparto grass. It grows by the seashore beyond high- water mark, and by the abundance of its creeping, fibrous, and entangled roots, assists in producing the elevated ridges known as .cand dunes, by retaining the grains of sand which otherwise would be carried by the wind farther inland. Eurytoma hyalipennis. The galls caused by this species on the marum grass are very interesting. The larva lives within the upper part of the haulm, and by its ravages prevents the further extension of that portion of the plant. The leaves, however, continue their growth, but not in the usual manner. The basal portion of one leaf spreads itself around another from the opposite side of the stem ; that leaf in turn is enveloped within another. This arrangement is multiplied until fifteen or twenty will thus embrace each other, forming a spindle-shaped bundle of stunted leaves. The leaves, converging just above the gall, continue to grow for a few inches, and assume their ordinary needle-like appearance. If the leaves be carefully removed, the gall proper will be readily found. It consists of a cylindrical-shaped swelling of the haulm, and shows on its surface where the leaves are attached to it. When cut open in the plane of its growth, the larval chamber will be seen. This cavity in some specimens is 40 mm. long and 2 mm. in diameter. The imagines emerge during June from the galls of the pre\ious year and immediately attack the tops of the young and tender haulms. By the end of July the galling agency is plainly visible, and at the end of September the larva is fully grown. It remains in an inactive condition through the winter, pupates within the gall during the spring, and emerges in June. The galls are seldom more than 12 in. above the level of the sand. Among several hundreds the author has collected and examined, none have been seen with two on one haulm. The illustration is of specimens gathered at Camber, near Rye, by the author. I'r.A'i'K 41. Haulms of Ammopliila ariinJiiiacca Host. Eurytoma hyalipcnnis. (NAT. 5.2E ) Galls caused by the larvae of Rhodites spinosissimse Giraud on the stems and leaves of Rosa spinosissima Linn. PLATE J^2. Synonymy of Insect. Rhodites spinosissivice, Schen., Tasch., Mayr, Cameron. Habitat of the Burnet, or Scotch, Rose.— This rose is common in Scotland, but not in England and Ireland. It is generally found on dry and bushy wastes, and is essentially a maritime plant. The Gall is formed by an accumulation of sap around the ova producing large swellings in the medullary tissue. Position.— On the stem, leaves, leaf-stalks, and sometimes flower-buds and petals. Manner of Growth.— Conglomerated ; glabrous ; glossy. Colour.— Green ; when mature, dull or bright red. Average Dimensions of a Mature Specimen.— On a stem. Length, 32 mm. ; on a leaf, girth, 36 mm. May be sought during the months of June, July, and August. The Growth is complete by the end of July. The Typical Condition of the gall is plurilocular. Usual number of cells, 8. The Larv^ pupate in the gall. The imagines emerge during the autumn. I NQUILINE.— /-^r/^/w/wj ca)ii7i(z. Parasites.— r^^/jw^j viacropterus, T. difficilis Nees., Mega- stigvius tmnsversus Walker, Pterotnalus inflexus Fo^r., P. incrassatus Ratz. The gall is also figured by Cameron, " British Phytopha<-ous Hymenoptera," vol. iv., plate 11. •'ft, "3 8 Rhodites spinosissimse. The galls of this species are placed very conspicuously on the plant. At first soft and succulent, they are green in colour, then tinged or suffused with pink, deepening into red, ultimately becoming almost fiery red in appearance, and hard and woody in texture. They are very irregular in outline, and occur on the stem with as much frequency as on the leaves. After the parent insect has deposited her ova, those in stem quickly cause comparatively large swellings in the medullary tissue, the surface being almost as closely beset with prickles as are the unaffected portions of the stem. When the leaves are attacked, the gall-growth may occupy the whole of one side of a leaflet, or both sides, with the serrated edge forming a kind of fringe around the swelling. The leaf-stalk and stipules also are sometimes the bearers of galls, while the flower-buds and the petals are occasionally galled. As com- pared with the size of the leaves, the galls are very large and cause the premature decay and falling off of those affected. The plant is known as the burnet, or Scotch, rose. In a wild state it rarely attains more than lo or 12 in. in height, and is generally found in dry and bushy land near the sea. Even under cultivation it seldom attains more than 2 ft. At Tenby, in South Wales, it is known as the burrow-rose, and is "of very stunted growth, just creeping along the ground, with small flowers which look very pretty among the grass." The illustration is of specimens gathered at Tenby by Mr. Walter Field. Platk 42. Stems of Rosa s/i/ws/'ss/mu L'u Rhodites spinosissiime Giraud. Galls caused by the larvae of Xestophanes brevitarisis Cam. on the stems of Potentilla tormentilla Sibth. PLATE 43. Synonymy of Insect. Aulax brevitarisis Opusc. Xestophanes tornientillce Schl., Cameron. Habitat of the Tormentil. — This plant is common in most parts of Britain, in open places in woods and by the sides of footpaths through them ; it is also found on moors and heaths. The Gall is formed by a gradual and persistent accumu- lation of sap around the ova deposited beneath the cuticle of the plant. Position.— On the stems. Manner of Growth. — Gregarious; conglomerated; sessile; slightly pubescent. Colour. — At first, green, later pink, changing to purple, and, when mature, nut-brown. Average Dimensions of a Cluster of Mature Speci- MEN.S. Length, 13 mm. ; breadth, 7 mm. ; girth, 18 mm. May BE sought during the months of June to November. The Growth is complete by the end of October. The Typical Condition of the gall is plurilocular. Usual number of cells, 10. The Larv.e pupate in the cells. The imagines emerge during the spring. These galls are very local in their situations, and are very persistent on the same plants year after year. They may be found in plenty in one spot, but a cluster of the same plants fifty yards away will not be affected. The gall is also figured by Peter Cameron, " British Phyto- phagous Hymenoptera" (Ray Society), vol. iv., plate 11. "5 Xestophanes brevitarisis. The graceful plant which is so freely attacked by this insect is a general favourite with all persons interested in botany. It, however, possesses additional interest to the gallist, because of the swellings caused upon its delicate and slender stems by X. brevitarisis. The enormous size of some of the galls as compared with the girth of the slender stem is remarkable. One example may be mentioned. In a wood near Hastings the author found, among other stems, one which measured 3 mm. only in girth. The swelling upon it was 22 mm. in girth; it contained 41 cells, and occupied a space 18 mm. in length. The galls occur mostly as conglomerated masses of cells, but examples of a single cell are not uncommon. Two such will be seen in the lower right-hand corner of the illustration near the flower. Galls of one cell only are usually spherical in shape, but when numbers are massed together they assume a reniform shape, and the uneven outline then produced distin- guishes them from the smooth growths caused by X. potcntilix on R. reptans. X. brevitarisis is an interesting species to study ; but as the galls will not develop so well after being severed from the root, even though the stems are placed in water, they should be obtained when growth is mature, or the entire plant removed to a convenient place for observation. The illustration is of specimens gathered at Hastings by the author. Pl.ATK 43. Stems of Potentilla tormciitilla Silith. Xestophanes hrevilarisis Cam. (TWO-TIIIRDS NAT. SIZE.) To face page 116. Galls caused by the larvoe of Xestophanes potentillae Cam. on the stems of Potentilla reptans Linn. PLATE 44. Synonymy of Insect. Cynips potentillcB De Vill. Aulax splendens Htg. „ poteiitilhc Schenck, Marshal!, Mayr. „ abbreviatus Thorns. Habitat of the Cinquefoil.— Along hedgerow banks, edges of woods, borders of meadows, by the side of most country lanes ; abundant in Britain, except parts of Scotland. The Gall is formed by a gradual and persistent accumulation of sap around the ova deposited beneath the cuticle of the stem. Position. — On the stems, and occasionally on the leaf-stalks. Manner of Growth. — Conglomerated ; .sessile ; glabrous. Colour. — At first green, later pink, changing to purple ; when mature, nut-brown. Average Dimensions of a Mature Specimen. Length, 8 mm. ; girth, 12 mm. May be sought during the months of July to November. The Growth is complete by the end of October. The Typical Condition of the gall is plurilocular. Usual number of cells, 6. The Larv/E pupate in the gall. The imagines emerge during the spring. Parasites. — Torymus globiceps Nees., T. ater Nees., Oligosthenus tibialis Nees., Eucyrtus zcphyrinus Dalman, Pezomacluis potentilla Gir. Like X. brcvitarisis, this species attacks the same plants year after year, leaving other clusters of Potentilla reptans untouched. The gall is also figured by Peter Cameron, " British Phy- tophagous Hymcnoptera" (Ray Society), vol. \\\, plate 11. 117 Xestophanes potentillae. The plant Potoitillce reptans may be easily distinguished from its congener, P. toniientil/a, by the facts that its leaves are pedunculated instead of sessile, much larger in size, and ordi- narily composed of five leaflets coarsely serrated in outline ; the petals, although the same colour as those of P. tormentilla, are larger and ordinarily five in number, but the stems are not so erect. When Xestophanes potetitilla; lays its eggs during the month of June, the punctures give rise to peculiar, oval-shaped, and irregular-sized swellings, sometimes projecting more on one side of the stem than another, but generally the swelling is evenly distributed, with a tendency to assume a spindle shape. The gall-growths occur along the stems singly, or in twos and threes at irregular intervals from the root to the last leaf, and also on the petioles. During the first few weeks of growth the swellings are soft and succulent, greenish or pinkish in colour ; later, however, the texture becomes more woody, and ultimately hard. The colour changes to a nut-brown, and growth is complete. The dimensions of the galls are very variable. A single cell will seldom be found exceeding i6 mm. in girth, whereas swellings containing six or seven cells will attain 30 mm. in girth and 15 mm. through its long axis. Anastomosis is neither so frequent nor so pronounced as in X. tormentilla, but examples are occasionally found where many grow upon the stems, and resemble small peas threaded on stout string. The illustration is of specimens gathered at Battle by the author. Platk 44. Stems of Potentilta irpta Xestophanes potentilke Cam. (FOUR-FIFTHS NAT. SIZE.) THE LEAF^GALLS. The Leaf-galls are those situated upon, within, or enclosed by the Blade, the Petiole, the Stipules, the Bract, or the Scales, or any of these parts enfolding Larva;. Eriophyes ajug/E Nalepa. PLAJE ^5, Galls caused by Eriophyes ajugae Nalepa on the radical leaves of Ajuga reptans Linn. PLATE 45. These leaves grew from the same scions as the galled flower- spikes illustrated on plate 118. The mites establish themselves on the upper surface of the radical leaves and cause the edges to curl upwards and slightly inwards, forming a somewhat irregular-shaped pod, within which may be one or two smaller leaves. At first no change of colour takes place on the exterior of the leaf; but ultimately it becomes suffused with purple and is somewhat swollen. Meanwhile, the interior, or upper surface, is, as a result of the action of the mites, becoming coated with a thick layer of short hairs, which at first are a yellowish colour, afterwards becoming paler and almost white. The exterior remains glabrous and glossy. A few of the scions should be placed in water in a shallow dish for the purpose of observa- tions. The plant will live a long while. See also p. 270. The illustration is of specimens gathered at Hastings by the author. Pl.ATK 45. / €f V \'\ %^ T I AV1.S t>K .iJiiK" np/aiis Linn. Eriophyes ajiif^te Nakpa. Eriophyes aucupari^. PLATE 40. Galls caused by the larvse, nymphs, and imagines of Eriophyes aucuparise on the leaves of Pyrus aucuparia Gsertn. PLATE 4G. Synonymy of Mite. Eriopliyes pyri Nal. Habitat of the Mountain Ash.— Distributed throughout Britain in woods, plantations, and parks. Position of the Galls. — On both sides of the leaflets and on the rachis. Manner of GRO^VTH.— Glabrous ; gregarious, coalescing into patches. Colour. — Pale green, yellow, orange-yellow, red, reddish brown. Average Dimensions of a Mature Specimen. Height, I mm. ; breadth, 2 mm. ; circumference, 6 mm. May be sought during the months of May to October. The Growth is complete by the end of August. These galls are very similar to those caused by Eriopliyes piri (p. 150) on leaves of Pyrus communis, not only in size, form, and colour, but also as regards coalescence, although this latter peculiarity is not quite so persistent. The swelling is in the form of a lenticular pustule, more fully developed when on the under surface of the leaflet than when on the upper. Although each leaflet may be thickly covered with the pustules, no appreciable difference is caused in the outline. The author has only twice found these galls, and he believes them to be both local and uncommon. See also plate 76. The illustration is of specimens gathered at Guestling, near Hastings, by the author. 124 Plate 46. Leaves of Pvnis aucuparia Grertn. Eriophyes auaiparhe. Eriophyes avellan/E Nalepa. PLATE Jt7. Galls caused by the larvae, nymphs, and imagines of Eriophyes avellanae Nalepa on the leaf-buds of Corylus Avellana Linn. PLATE J,7. Synonymy of Mite. Acarus pseudogallaruin Vail. Pliytoptus psetidogallai-uvi Canest, Tar-Tozz. „ coryli Murr., Franeuf. „ avellancB Nalepa. Habitat of the Common Hazel.— Ubiquitous in Britain in woods, thickets, and hedges. Position of the Galls.— The leaf-buds themselves con- stitute the galls. Manner of Growth. — Singly ; slightly pubescent ; semi- globular, and cone-shaped. Colour. — Green, suffused with reddish brown and chocolate- brown. Average Dimensions of a Mature Specimen (cone- shape, gathered in February). Height, lo mm.; girth, 21 mm. May be sought during any month in the year. The Growth is complete by the end of May, In reality these galls may be found all the year round, but they are hardly worth gathering during July and August. The mites transfer themselves from the old to the new buds during that time. They completely destroy the growth of the leaves and catkins which otherwise would unfold from the buds. Some bushes in sheltered places are badly attacked, 75 per cent, of the buds being occupied with the creatures. A bud may consist of twenty-five to forty leaf-scales, the inner ones being somewhat thickened and woolly in appearance. The illustration is of specimens gathered at Hastings by the author. 126 Plate 47. Leaf-buds of Corrlus Avcllana Li Eriophyes Avellana Nalepa. (FOUR-FlFfHS NAT. SIZE.) ErIOPHYES iVXILLARIS. PLATE 4S. Galls caused by the larvae, nymphs, and imagines of Eriophyes axillaris on the leaves of Alnus glutinosa Linn. PLATE 48. Synonymy of Mite. Ef'ineuni axillarc Schl. Pliytoptus ahiicola Canes. „ altii Fock. Eriophyes Nalepi Fock. „ lavis Nal. Habitat of the Alder.— Abundant in Britain by the sides of streams, in woods where the ground is wet and swampy, and occasionally in more accessible places. Position of the Galls. — In the a.xils of the primary off- shoots from the mid-rib. Manner of Gro\VTH.— Always in pairs ; glabrous ; glossy ; globular ; ovid ; and reniform. Colour. — Yellowish green, red, dark brown. Average Dimensions of a Mature Specimen (reniform or ovid). Height, 3 mm. ; length, 5 mm. ; breadth, 3 mm. May be sought during the months of June to October. The Growth is complete by the end of August. These galls are remarkable in that they never occur on any other part of the leaf than in the axils of the primary offshoots from the mid-rib, and the bulging is always on the upper surface. The surface of the gall is smooth, but under magnification it is seen to be divided into sections of irregular size owing to cerebriformal markings. The gall is hollow, containing a considerable number of hairs of a reddish colour, many of which project for some distance through the opening in the under surface of the leaf The illustration is of specimens gathered at Hastings by the author. 128 Plate 48. Leavks oi-' Aliii/s i:/i/tii/osa Lii Eriophyes ax i liar i (FOUR-FIFTHS NAT. SIZE Eriophyes brevitarsus Nal. PLATE 49. Galls caused by the larvae, nymphs, and imagines of Eriophyes brevitarsas Nal. on the leaves of AInus glutinosa Linn. PLATE 49. Synonymy of Mite. Erineum alneian Pers. Phytoptus brevitarsus Nal. „ purpureum De C. Phyllerium alnigenum Kunze. Habitat of the Alder. — Abundant in Britain by the sides of streams, in woods where the ground is wet and swampy, and occasionally in more accessible places. Position of the Galls.— On the blade of the leaf; irregu- larly distributed. Manner of Growth. — Gregarious ; glabrous on upper surface, slightly pubescent beneath. Colour. — Pale green, very pale yellow, ultimately turning brown. Average Dimensions of a Mature Specimen. Height, 6 mm.; length, 18 mm.; breadth, 12 mm. May be sought during the months of June to October. The Growth is complete by the end of August. These galls cause considerable disfigurement of the leaf, and are found mostly on the young and expanding leaves near the end of the twig. They are convexo-concave, blister-like swellings. The upper surface is smooth and glossy ; the interior is slightly pubescent, the mites living therein. The blisters are somewhat irregular in shape, but are mostly ovid. They are not restricted to the areas enclosed between the primary and secondary offshoots from the mid-rib, but they also involve the mid-rib itself The illustration is of specimens gathered at Hastings by the author. '3° Plate 49. Leaves of A/niis i^li/tiiiosa Linn. Eriophyes brevitarsiis Nal. ErIOPHYES CRATvEGI. PLATE 60. Galls caused by the larvae, nymphs, and imagines of Eriophyes crataegi. on the leaves of Crataegus Oxyacantha Linn. PLATE 50. Synonymy of Mite. Habitat of the Hawthorn.— In woods and thickets through- out Britain ; also forming artificial hedges by the sides of railways, roads, and lanes. Position of the Galls.—Oh both surfaces of the leaf. Manner of Growth. — Gregarious ; glabrous ; coalescent. Colour. — Green, orange-yellow, dark brown. Average Dimensions of a Mature Specimen. Height, 4 mm. ; breadth, 2 mm. May be sought during the months of May to November. The Growth is complete by the end of September. These galls are mostly lenticular in shape, and are fairly evenly distributed on the upper surface, as well as on the under surface of the leaf They are situated on any part except the mid-rib and its primary offshoots, and are usually not very numerous. An average-sized leaf may have about a hundred galls upon it. The number depends very much upon whether the mites have been long established on the plant, which when in a hedge harbours them more effectually than when they affect the leaves of a hawthorn grown to a tree. In the illustra- tion many of the leaves show the under surface. The illustration is of specimens gathered at Hastings by the author. 132 Plate 50. kVES OF Cni/trnis 0.\\ac(i/i//ii Eriophyes cratccgi Canest. (NAT. SIZE.) Eriophyes galii Karp. PLATE 51. Galls caused by the larvae, nymphs, and imagines of Eriophyes galii Karp. on the leaves of Galium Aparine Linn. PLATE 51. Synonymy of Mite. Pliytoptiis galii Karp. Cecidophyes galii Nalepa. Eriophyes galii Nalepa. H.\1UTAT OF THE GooSE-GRASS. — This common herb is very- abundant in hedges, among brambles, and on banks all over Britain. Position of the Gall.— The entire leaf is affected, and forms the gall. Manner of Growth.— Gregarious. Colour. — Very pale green, ultimately yellowish green. Average Dimensions of a Mature Specimen. Length, 30 mm. ; girth, 5 mm. May be sought during the months of May to October. The Growth is complete by the end of August The peculiar contortions assumed by the leaves of this plant when attacked by the Eriophyes enable them to be easily recognised. Although the plant is ubiquitous throughout Britain, the galled condition is not often seen ; it appears to be uncommon and local. If gathered in the early part of May, the imagines may be seen (under magnification) in a lethargic condition, as also large masses of ova. Later in the month, and throughout June, the nymphs are very active and numerous. The specimen in the centre of the illustration is of a normally developed stem and leaves, and is introduced for the purpose of comparison with the others. The illustration is of specimens gathered at Guestling by Mr. F. Hall. "34 Plate 51. Leaves of Galium Aparine Linn. GALLED BY Eriophyes galii Karp. Eriophyes galiobius Can. PLATE 5S. Galls caused by the larvae, nymphs, and imagines of Eriophyes galiobius Canest. oil the terminal leaves of Galium verum Linn. PLATE 52. Synonymy of Mite. Phytoptus galiobius Can. „ informis Nalepa. Habitat of the Ladies' Bedstrav^t.— Very generally dis- tributed throughout Britain, growing on banks and pastures, preferably in a fairly dry situation. Position of the Gall.— At the top of the main stem ; some- times on the lateral shoots. Manner of Growth.— Singly ; glabrous ; mostly pyramidal in shape. Colour.— Pale green, yellowish, chocolate-brown. Average Dimensions of a Mature Specimen. Height, 8 mm.; girth, 15 mm. May be sought during the months of June to October. The Growth is complete by the end of August. These galls are found plentifully on plants growing on the golf-links at Camber, near Rye, Sussex. The ground is near to the sea, and is very sandy owing to its close proximity to the sand dunes which skirt the sea-shore at that part of the coast. The galls are deeply grooved or furrowed from base to apex. Some are almost globular in shape, others are elongated, while a few are like a miniature cupola. The author is indebted to Miss Ethel Sayer for her kindness in sending some very fine specimens from Mundesley, Norfolk. The illustration is of specimens gathered at Camber, Sussex, by the author. 136 Plate 52. . I.UMINAL 1. ':inii vcnini Linn. Eriophyes galiobius Canest. (NEARLY NAT. SIZE.) To face page 136. Eriophyes goniothorax Nal. PLATE 53. Galls caused by the larvae, nymphs, and imagines of Eriophyes goniothorax Nal. the leaves of Crataegus Oxyaoantha Linn. PLATE 53. Synonymy of Mite. Erineum cla7idestinum Gerv. „ oxyacanthcE Vail., Amer., Murr. Phytoptus goniothorax Nal. Habitat of the Hawthorn. — In woods and thickets throughout Britain ; also forming artificial hedges by the sides of railways, roads, and lanes. Position of the Galls. — On the edges of the lobes of the leaves. Manner of Growth.— The edge of the lobe curls downwards and under. Colour. — Variable, but usually paler than the other part of the leaf Average Dimensions of a Mature Specimen. Length, lo mm. ; breadth, i mm. May be sought during the months of May to November The Growth is complete by the end of September. The galled edges are more easily seen when the leaf is looked at from below than from above. Two opposite edges which are attacked will roll towards each other until they meet and transform the lobe into a small spike. It is not often that more than ten lobes of a leaf are attacked ; the usual number is si.K. The gall is also figured by Nalepa, " Beitrage zur Systematik der Phytopten," Taf ix. The illustration is of specimens gathered at Eastbourne by the author. 138 Plate 53. Leaves of Cra/tcxi/s Oxyaiiuitkn Linr Eriophyes goiiiof/iorax Nal, Eriophyes i^JEVis Nal. PLATE 54. Galls caused by the larvae, nymphs, and imagines of Eriophyes laevis Nal. on the leaves of Alnus glutinosa Linn. PLATE 54. Synonymy of Mite. Phytoptus Icsvis Nalepa. Cephaloneon pustulatum Biemi. Habitat of the Alder. — Abundant in Britain by the sides of streams, in woods where the ground is wet and swampy, and occasionally in more accessible places. Position of the Galls.— On the upper surface of the leaves. Manner of Growth. — Gregarious ; glabrous; glossy; more or less globular and pedunculated. Colour. — Green, yellow, orange-yellow, bright red, purple, chocolate-brown. Average Dimensions of a Mature Specimen. Height, 2 mm. ; girth, 4 mm. May be sought during the months of May to October. The Growth is complete by the end of August. A little below the centre of the illustration are three galled leaves, the finest specimens possible to obtain. So numerous are the galls upon each leaf that, owing to the swelling of their globular portion, the blade of the leaf has been caused to bend under until a pouch has been formed. Several other leaves are so curved that the galls are seen silhouetted against the back- ground, furnishing an excellent description of the shapes they assume. These galls are extremely plentiful in many places ; some trees are loaded with them year after year. A leaf of average size may have as many as 400 galls upon it. The illustration is of specimens gathered at Hastings by the author. 140 ATK 54. Llaves of Alnus gli/tiiitsa Linr CALLED liV Eriophyes lav is Nal. (THREE-FOURTHS NAT. SIZE.) Eriophyes lionotus Nal. PLATE 65. Galls caused by the larvae, nymphs, and imagines of Eriophyes lionotus Nal. on the leaves of Betula alba Linn. PLATE 65. Synonymy of Mite. Phytoptus leionotus (corr. lionotus) Nal. Ceplialoneon betulinum Bremi. Phyllermm [Erineuni) tortiiosuni Gerv. Habitat of the Common Birch.— Plentiful all over Britain in parks, plantations, woods, and gardens. Position of the Galls. — In the nerve-axils of the leaf. Manner of Growth. — One in each axil ; generally six on a leaf Colour. — Reddish brown on upper surface, reddish pubescence on under surface. Average Dimensions of a Mature Specimen. Height, 1 1 mm. ; length, 4 mm. ; breadth, 2 mm. May be sought during the months of May to October. The Growth is complete by the end of August. These galls are at first somewhat inconspicuous, but during August they become very pronounced in outline, rising above the level of the surrounding surface of the leaf-blade to a height of 2 or 3 mm. They are mostly obtusely elliptical in outline, and sometimes extend from one nerve-axil to the next beyond it, the outline being then very irregular. The convexo-concave swelling is filled with pubescence, which projects considerably, and amongst it the mites may easily be seen under magnification. The illustration is of specimens gathered at Guestling, near Hastings, by the author. 142 Plate 55. Leaves of Betiila alba Linn. Eriophyes Uonotiis Nal. Eriophyes macrochelus Nal. PLATE 56. Galls caused by the larvae, nymphs, and imagines of Eriophyes macrochelus Nal. on the leaves of Acer campestre Linn. PLATE 5G. Synonymy of Mite. Erineuni purpurascens Gaertn. Phyt Optus moniezi Fock. „ macrocJielus Nal. Cephaloneon solitariu7n Bremi. Habitat of the Common Maple. — Abundant in southern England, but less plentiful in the north and in Scotland. It is found in woods and hedges, the latter situation being the favourite. Position of the Galls. — On the upper surface of the leaf Manner of Growth. — Usually gregarious ; globular, ovid, and reniform in shape. Colour. — Green, orange-yellow, red, brown. Average Dimensions of a Mature Specimen (reniform shape). Height, 4 mm. ; length, 6 mm. ; breadth, 3 mm. May be sought during the months of June to November. The Growth is complete by the end of August. These galls are exceedingly variable in many ways. They may be solitary or coalesced, gregarious or single, sessile or semipedunculated, glabrous or pubescent, glossy or dull, and triplicate in shape. They are larger and not so numerous as those caused by E. macrorhyncus, and they are more confined to the primary offshoots from the petiole. Occasionally they de- velop on the under surface of the leaf The cell-walls are very thick and woody. A leaf of average size may have from fifty to two hundred galls upon it without causing any distortion. Some leaves are entirely covered with them : the deformity is then very great. The gall is also figured by Nalepa, " Neue Gallmilben," Taf XV. The illustration is of specimens gathered at Hastings by the author. 144 Plate 56. / j^- ' ^::^. Leaves of Acer annpcs/rc Linn. Eriophycs iiiacrochelus Nal. Eriophyes macrorhyncus Nal. PLATE 57. Galls caused by the larvse, nymphs, and imagines of Eriophyes macrorhyncus Nal. on the leaves of Acer campestre Linn. PLATE 57. Synonymy of Mite. Ceplialoneon myriadeum Bremi. Phyloptus macrorhyncus Nal. „ viyriadeuni Murr. Phyllocoptcs aceris Nal. Habitat of the Common Maple.— Abundant in southern England, but less plentiful in the north and in Scotland. It is found in woods and hedges, the latter situation being the favourite. Position of the Galls.— On the upper surface of the leaf. Manner of Growth. — Gregarious ; glabrous ; semi-globular pimples. Colour. — Greenish yellow, red, purple, reddish brown. Average Dimensions of a Mature Specimen. Height, I mm. ; girth, 3 mm. May be sought during the months of June to November. The Growth is complete by the end of August. It is remarkable how many of these galls are sometimes crowded on the leaves. From 400 to 500 is quite a usual number. In 1899 the author discovered a small maple-bush in a hedge in Norfolk, and upon many leaves of average size he counted from 600 to 8 50 galls ; one rather large leaf contained nearly 1,400. Their number does not very greatly affect the contour of the leaf. When they are purple in colour a very pretty and attractive object is produced. Examination of the under surface with a lens will show numbers of minute de- pressions, which are the openings of the galls. The gall is also figured by Nalepa, " Neue Gallmilben," Taf. XV. The illustration is of specimens gathered at Hastings by the author. Platk 57. Lkaves ok Ait'r cainpcstrc Linr- CALLED BV Eriophyes macrorhyticus Nal. (THREE-FOURTHS NAT. SIZE.) Eriophyes marginatus. PLATE SS. Galls caused by the larvae, nymphs, and imagines of Eriophes marginatus on the leaves of Salix alba Linn. PLATE 58. Habitat of the White Willow.— By the side of streams, in marshes, and in hedges around damp meadows. Common all over Britain. Position of the Galls.— On the margins of the leaf. Manner of Growth.— Singly ; glabrous ; sessile. Colour. — Pale green, greenish yellow, orange-yellow, red, brown. Average Dimensions of a Mature Specimen. Height, I mm. ; length, 3 mm. ; breadth, i mm. May be sought during the months of June to October. The Growth is complete by the end of August. These galls often have the appearance of being attached to the margin of the leaf by a short peduncle ; they are, however, sessile. They rarely coalesce, but the ends of several when close together meet, and cause the margin of the leaf at that part to curl considerably. They vary in number from two or three to fifteen on one leaf, and are always situated on the margins. The oldest and largest leaves seem to be less liable to attack than those younger and near the end of the twig. They appear to be very local, and are not plentiful where they occur. The illustration is of specimens gathered at Hastings by the author. 148 Plate 58. Lkaves of Sd/i'x alba Linn. Eriophyes margiiiatits. (FOUR-FIFTHS NAT. SIZE.) Eriophyes piri Nal. PLATE 59. Galls caused by the larvae, nymphs, and imagines of Eriophyes piri Nal. on the leaves of Pyrus communis Linn. PLATE 59. Synonymy of Mite. Phytoptus pyri Murr. „ piri Nal. „ arianus + Phytoptus cotoneastri + Phytoptus sorbi Pgst „ aronim Canest. Typhlodromus pyri Scheut. Habitat of the Pear-tree. — Cultivated in orchards and gardens throughout Britain. Position of the Gall. — On both surfaces of the leaf. Manner of Growth. — Gregarious; glabrous; coalescent. Colour. — Pale green, reddish, chocolate-brown. Average Dimensions of a Mature Specimen. Height, I mm. ; length, 3 mm. ; breadth, 2 mm. May be sought during the months of May to October. The Growth is complete by the end of July. Not infrequently a leaf will be completely covered with the small eruptive pustules caused by these mites. The out- line of the leaf is seldom distorted, but the surface is sometimes much wrinkled and blistered by the large number of the galls. The galls are hollow, and the mites gain access through a minute hole, which, with the aid of a lens, may be seen in the under surface of the leaf This disease of the pear leaves appears to be very common throughout the country, and some- times considerable damage is caused to the foliage. The gall is also figured by Miss Ormerod, " Orchard and Bush-fruit Insects," p. 127; Murray, "Economic Entomology," P- 359- The illustration is of specimens gathered at Guestling, near Hastings, by the Rev. E. N. Bloomfield, M.A., F.E.S. ISO Plate 59. '^^ A. A, UI'l'ER SURFACK, B. B. UNDER SURFACE, Leaves or FjrHS comniunis Linn. GALLED BY Eriophyes piri Nal. (FOUR-FIFTHS NAT. SIZE.) Eriophyes psilaspis Nal. PLATE GO. Galls caused by the larvae, nymphs, and imagines of Eriophyes psilaspis Nal. the buds of Taxus buccata Linn. PLATE 60. Synonymy of Mite. Phytoptus psilaspis Nalepa. „ taxi Murray. Tetranychus taxi Murray. Habitat of the Common Yew.— This tree may be found in the graveyards of many rural churches throughout Britain ; also in parks and private grounds, where it is frequently cultivated as hedges. Position of the Galls.— The leaf-buds themselves constitute the galls. Manner of Growth. — Singly and gregarious ; glabrous ; semi-globular, and pineal in shape. Colour. — Dark green, changing to reddish brown or chocolate- brown. Average Dimensions of a Mature Specimen (pineal form). Height, lo mm. ; greatest girth, 24 mm. May be sought during any month in the year. The Growth is complete by the end of May. The two small twigs have been introduced in the illustration to show the difference between the immature fruit and the growing galls. These galls are very numerous on some yews, more especially when employed as hedges. The mites are very persistent in the buds, and attack them as soon as they develop from the twig, prevent their normal growth, retard the development of the new wood, and produce dwarfed and stunted bushes. The remark anent collecting the buds of Corylus Avellana (p. 126) applies also to these buds. The gall is also figured by F. V. Theobald, "S.E. Ag. Coll. Journal," March, 1899. The illustration is of specimens gathered at Hastings by the author. Biiib vt 2'(i.\ti> i'liiidta Lini: Eriophyes psihispis Nal. Eriophyes pustulatum. PLATE 61. Galls caused by the larvae, nymphs, and imagines of Eriophyes pustulatum the leaves of Populus tremula Linn. PLATE 61. Synonymy of Mite. Habitat of the Aspen. — This tree grows well in coppices, woods, and forests. It may also frequently be seen in profusion on the outskirts of a wood by the side of a stream. Position of the Gall. — Projecting from the upper and under surfaces of the leaf Manner of Growth. — Separate; sessile; glabrous; glossy. Colour.— Greenish yellow, orange-yellow, red, purple. Average Dimensions of a Mature Specimen. Height, 2 mm. ; girth, 5 mm. May be sought during the months of June to October. The GrO\vth is complete by the end of August. These galls appear to be very local, and nowhere abundant. About equal proportions of the gall project from each surface of the leaf There are seldom more than four or five galls on an average-sized leaf Two leaves on the right-hand side of the illustration show the under surface and the little hole in each gall through which the Eriophyes leave and enter the swelling. Unfortunately our illustration does not do fullest ju-;tice to these very pretty and interesting little galls. The illustration is of specimens gathered at Hastings by the author. Lkavks oi' J'dpii/iis lii'iiiiila Eriophyes piisliilatiiiii. Eriophyes ribis Nal, PLATE 63. Galls caused by the larvae, nymphs, and imagines of Eriophyes ribis Nal. on the leaf-buds of Ribes nigrum Linn. PLATE 62. Synonymy of Mite. Phytoptus ribis West, Nalepa, Mum, Ormerod (Miss). Habitat of the Black Currant. — Cultivated in gardens and orchards throughout the whole of Britain. Bentham in "British Flora," p. 164, says: "If anywhere wild, it is in the Lake District and Yorkshire." Position of the Galls.— On the shoots. Manner of Growth. — Singly at each node and in clusters at the end of the twig. Colour. — Ashy grey. Average Dimensions of a Mature Specimen (gathered in April). Height, 12 mm.; girth, 30 mm. May be sought during any month in the year. The Growth is complete by the end of May. These galls are, unfortunately for the fruit-grower, only too well known to need any detailed description. Much has been written and published concerning them since they were first brought to public notice in this country in 1869, and the gallist desirous of aiding or confirming his examinations of them cannot do better than consult the under-mentioned works. The remark anent collecting the buds of Corylus Avellana (p. 126) applies also to these buds. The gall is also figured by Miss Ormerod, " Injurious Insects," p. 303, and "Orchard and I3ush-fruit Insects," p. 60; Murray, "Economic Entomology," p. 355 ; Mosley, " Naturalists' Journal," May, 1895. The illustration is of specimens gathered at Hastings by the author. 156 Plate 62. LiiAF-BUDS OF Rll'es /i/,i;ri///i Linn. Eriophyes ribis Nai. (THREE-FOURTHS NAT. SIZE. To face page 156. Eriophyes rudis Canest. PLATE 63. Galls caused by the larvae, nymphs, and imagines of Eriophyes rudis Canest. on the leaf-buds of Betula alba Linn. PLATE 63. Synonymy of Mite. Phytoptus rudis Canestrini. „ calycophthirus Nalepa. Habitat of the Common Birch.— Plentiful all over Britain in parks, plantations, woods, and gardens. Position of the Gall.— On the twigs and branches. Manner of Growth. — Singly and in clusters ; pubescent and glossy. Colour.— Outer leaflets dull brown, inner ones silvery grey. Average Dimensions of a Mature Specimen (a single bud). Height, ID mm. ; girth, 27 mm. May be sought during any month in the year. The Growth is complete by the end of August. The galls are very numerous, and occur in clusters of con- siderable numbers. They develop into three principal forms: {a) at the termination of a twig with a hard, solid, and woody core, from which numerous twigs project, as shown in plate 16; ij)) from any part of a twig or branch, and without any core, as shown in plate 17 ; {c) from the side of a branch with a hard, solid, and woody core, which also forms a part of the branch, as shown in plates 18, 19, and 20. The gall is also figured by Miss Ormerod, " Injurious Insects," pp. 212, 214. The illustration is of specimens taken from the tree at Guestling by the author. 158 Plate 63. Leaf-buds ok Bftiila nlha Lin Eriophyes nuiis Canest. Eriophyes sanguisorb^ Nal. PLATE 64. Galls caused by the larvae, nymphs, and imagines of Eriophyes sanguisorbae Nal, on the leaflets of Poterium sanguisorba Linn. PLATE 6i. Synonymy of Mite. Phytoptus sanguisorbcE Canest. Erineum ■t>oterii De C. Habitat of Salad Burnet. — In dry pastures ; found mostly in the limestone and chalk districts of England, but scarce in Scotland and Ireland. Position of the Galls. — On the leaflets. Manner of Growth. — Each alTected leaflet becomes coated with pubescence. Colour. — Pale straw colour. Average Dimensions of a Mature Specimen (a single leaflet). Length, 8 mm. ; breadth, 4 mm. ; girth, 10 mm. May be sought during the months of June, July, and August The Growth is complete by the end of July. These pretty little galls are described by Nalepa (" Katalog der bisher beschriebenen Gallmilben," p. 298) as " Abnormer Haarfilz an der Blattern und Stengeln " (" abnormal felt of hair on the leaves and stalks"). They are exceedingly pubescent, and in specimens in which the three apical leaflets are swollen and thickly covered with hairs the appearance is that of a tuft of wool. The illustration is of specimens gathered near Goodwood by Mr. R. R. Hutchinson. 160 Plate 64. ^ :\<. ^ ^ Lic.wES oi- PoUi-ium Siiiigidsorba Linn. Eriophyes saiiguisorlw Nal. Eriophyes similis Nal. PLATE 65. Galls caused by the larvae, nymphs, and imagines of Eriophyes similis Nal. on the leaves of Prunus spinosa Linn. PLATE 65. Synonymy of Mite. Cephaloncoii hypocrateriforine Bremi. PhytopUis attenuatus Murr. „ similis Nalepa. Habitat of the Sloe-tree. — Abundant in Britain, in a wild state, in hedges, thickets, and open woods ; cultivated in almost every orchard. Position of the Gall. — Principally on the upper surface of the leaves. Manner of Growth.— Gregarious ; pubescent. Colour. — Greenish yellow, yellow, orange, purple. Average Dimensions of a Mature Specimen. Height, 2 mm. ; girth, 6 mm. May be sought during the months of May to October. The Growth is complete by the end of August. These galls occur also on the leaves of the plum, greengage, damson, and bullace, and are all so much alike that illustra- tions of each are not necessary. On some leaves they are so numerous as to cause considerable distortion. The largest number the author has seen on one leaf is fifty-four. They were distributed all over the leaf and also along the margins. The leaf measured 65 mm. long and 35 mm. broad. The aperture of the gall is in the under surface of the leaf ; it is irregular in outline, and is fringed with very fine hairs. The illustration is of specimens gathered at Hastings by the author. 162 Pl.ATK 6 = ^^^M Leaves of Pnoius spinosa Linn. Eriophyes similis Nal. To face page 162. Eriophyes tetanothrix L/EVis Nal. PLATE 6P. Galls caused by the larvse, nymphs, and imagines of Eriophyes tetanothrix IsBvis Nal. on the leaves of Salix Gaprea Linn. PLATE 66. Synonymy of Mite. Cecidophyes tetanothrix Nal. Phytoptus tetanothrix Nal. Habitat of the Sallow- or Goat-willow.— Very com- mon throughout Britain by the sides of streams, marshy places, damp open woods, and in thickets and hedges. Position of the Gall.— On the upper surface of the leaf. Manner of Growth. — Gregarious ; pubescent ; separate and also coalescent. Colour. — Green, red, reddish brown. Average Dimensions of a Mature Specimen. Height, 3 mm. ; girth, 9 mm. May be sought during the months of June to October. The Growth is complete by the end of August. The mites enter and leave the gall through an aperture which is situated on the underside of the leaf The aperture may be circular, oval, elliptical, or irregular in outline. When this portion is viewed under magnification, numerous purple-coloured spots can be seen studding the margin. The gall-structure is pilose on the upper surface of the leaf and glabrous beneath. A longitudinal section shows the walls to be very thick. The interior is filled with long, thin hairs, many of which project a short distance beyond the aperture. These galls occur in considerable numbers, some leaves having as many as twenty-five upon them. The gall is also figured by Murray, " Economic Entomology," P- 337. The illustration is of specimens gathered at Hastings by the author. 164 Pl.ATK 66. Lkavks of Sa/ix Ci/'i-ca Lmn. Eriophyes Maiio/hrix Ams Nal. Eriophyes tetratrichus Nal. PLATE 67. Galls caused by the larvae, nymphs, and imagines of Eriophyes tetratrichus Nal. on the leaves of Tilia europaea Linn. PLATE 67. Synonymy of Mite. Legnon crispuni Bremi. Phytoptus tetratrichus Nal. Habitat of the Common Lime-tree. — This tree occurs throughout Britain in woods, parks, avenues, etc. It is profuse in its foliage and flowers, and assumes handsome and noble proportions. Position of the Galls. — Around the margins of the leaf. Manner of Growth.— A rolling and slight thickening of the edge, which may extend all round the leaf Colour. — Green, orange-yellow, reddish brown. Average Dimensions of a Mature Specimen. Length, 30 mm. ; breadth, i^ mm. May be sought during the months of June to October. The Growth is complete by the end of August. The serrations on the edge of the leaf are first attacked by these mites, causing them to curl upwards and to bend over until they touch the upper surface of the leaf The rolling is continued until it has extended all round the leaf, and also until but a small portion remains in the centre, which is much pouched. The exterior of the roll is slightly pubescent, the interior very pilose. The apparently small leaf in nearly the centre of the illustration was originally the size of that next below it. The crinkled appearance of the leaves is due to shrivelling before being photographed. The illustration is of specimens gathered at Aylsham, Norfolk, by the author. 166 Platk 67. Leaves of Tilia curapica \m\\\. Eriophycs tetratrkhus Nal. To face page 166. Eriophyes tili^ (typicus) Nal. PLATE 68. Galls caused by the larvae, nymphs, and imagines of Eriophyes tiliae (typicus) Nal. on the leaves of Tilia europaea Linn. PLATE 68. Synonymy of Mite. Ceratoneon extensum Bremi. Phylleriuni {Erineum) tiliaceum Pers. „ „ nervale Kunz. Eriophyes tilia (typicus) Pgst. Habitat of the Common Lime-tree.— This tree occurs throughout Britain in woods, parks, avenues, etc. It is profuse in its foliage and flowers, and assumes handsome and noble proportions. Position of the Galls. — On upper surface of the leaf. Manner of Growth. — Gregarious ; glabrous ; glossy ; conical. Colour.— Greenish yellow, red, crimson, purple, brown. Average Dimensions of a Mature Specimen. Height, 8 mm.; girth, 6 mm. at base. May be sought during the months of June to October. The Growth is complete by the end of July. These galls never fail to arrest the attention of the gallist. The shape, the various colours, and the large numbers, all com- bine to render them very conspicuous. They are known as the " nail-gall," and look very like the points of a number of tacks projecting through the upper surface of the leaf. They are hollow, the interior containing a quantity of long hairs, amongst which the mites swarm in considerable numbers. An average size leaf may have as many as 150 galls upon it, and yet be free from other deformities. The gall is also figured by Murray, "Economic Entomology," P- 332- The illustration is of specimens gathered at Aylsham, Norfolk, by the author. Li:a\i;s of Tilia curop(ea Lini Eriophyes tilUe (typicus) Nal. To face page i68. Eriophyes tiliarius. PLATE 69. Galls caused by the larvae, nymphs, and imagines of Eriophyes tiliarias on the flower-bracts of Tilia enropaea Linn. PLATE 69. Synonymy of Mite. Phytoptus tiliarius Mur. Habitat of the Common Lime-tree.— This tree occurs throughout Britain in woods, parks, avenues, etc. It is profuse in its foliage and flowers, and assumes handsome and noble proportions. Position of the Galls.— On the margin of the flower-bract. Manner of Growth. — Separately; sessile; slightly pubescent. Colour. — Green, suffused with red and reddish brown. Average Dimensions of a Mature Specimen. Length, 20 mm. ; breadth, 2 mm. May be sought during the months of June, July, and August. The Growth is complete by the end of July. These galls begin to form on the margin of the bract as small elevations. The feeding of the mites causes the edge of the bract to rise upwards and curl over towards the mid-rib, pro- ducing a roll which sometimes extends 30 to 40 mm. in length, and continues to roll over upon itself until the middle of the bract is reached. When thus affected the bract may curve into a crescent shape, the roll itself forming the inner margin of the concavity, or it may be otherwise considerably distorted. No harm is done to the flowers, nor does the bract fall until the usual time, hence the mites are not destructive to the fruit. The gall is also figured by Murray, "Economic Entomology," P- 356. The illustration is of specimens gathered at Aylsham, Norfolk, by the author. 170 Plate 69. Flowkr-buacts ok 'J ilia (uropu Eriopliycs tilinrim. To face page 170. Eriophyes tristratus, var. erinea Nal, PLATE 70. Galls caused by the larvje, nymphs, and imagines of Eriophyes tristratus, var. erinea Nal. on the leaves of Juglans regia Linn. PLATE 70. Synonymy of Mite. Erineum jiiglandinuni Pers., Murray. I. juglattdis Ung. Phyllerium juglattdis Schl. Phytoptus tristratus, var. erinea Nal. Habitat of the Walnut-tree. — It is well distributed throughout Britain in private grounds and parks, and also on farms. Position of the Galls. — On the leaflets, in the areas en- closed between the primary and secondary offshoots from the mid-rib. Manner of Growth. — Singly or in numbers ; glabrous on upper surface, pubescent on under surface. Colour. — Greenish yellow, suffused with reddish brown. Average Dimensions of a Mature Specimen. Height, 5 mm. ; length, i6 mm. ; breadth, lo mm. May be sought during the months of June to October. The Growth is complete by the end of August. The presence of the mites on the under surface of the leaf is first shown by the growth of pale yellow hairs on the parallel secondary offshoots from the mid-rib. The area which they enclose then becomes pilose, and at the same time a slight discoloration and elevation of the upper surface is noticeable. The deformities increase until a convexo-concave swelling is produced, the interior of which is filled with a thick felt of pubescence of a pale buff colour. See also plate 75. The illustration is of specimens gathered at Guestling, near Hastings, by the author. 172 Platk 70. L.KAVES OF Jughiiis tcgia Liiiti. Eriophyes tristratiis, var. eriwa, Nal. Eriophyes viburni. PLATE 71. Galls caused by the larvae, nymphs, and imagines of Eriophyes viburni on the leaves of Viburnum opulus Linn. PLATE 71. Habitat of the Guelder Rose.— In woods, coppices, and hedges, more or less plentiful throughout Britain. Position of the Gall.— On the upper surface and the under surface of the leaf. Manner of Growth. — Irregular-shaped patches. Colour. — Reddish brown, chocolate-brown. Average Dimensions of a Mature Specimen. Height, 2 mm. ; breadth, 8 mm. May be sought during the months of June to October. The Growth is complete by the end of August. These galls vary from the size of a mere speck to aggre- gations which cover two-thirds of the area of a leaf They are not common, and appear to be very local ; but where the mites have been long established on a tree, the galls are very numerous. The author once found a twig, 4^ in. long, bearing twelve leaves, nine of which were more or less attacked by the mites. Unfortunately, it was not possible to preserve it for photographing. The illustration on the opposite page is the best procurable at the time of writing the description. It is hoped that it may be some help to the gallist for the purpose of identification. The illustration is of specimens gathered at Hastings by the author. Leaves of Vihuniiim Opiilui l.iiin. Eriophyes Vitnirni. To face page 174- MONOCHETUS SULCATUS Nal. PLATE 72. Galls caused by the larvae, nymphs, and imagines of Monochetus sulcatus Nal. on the leaves of Fagas sylvatica Linn. PLATE 72. Synonymy of Mite. Monaulax sulcatus Nal. Habitat of the Common Beech. — A large and tall tree of majestic and noble proportions. Grows in woods and forests in every part of England, where it is extensively planted. Position of the Galled Leaves. — Mostly at the end of a twig. Manner of Growth. — Villous ; cymbiform ; seldom more than six affected leaves on one twig. Colour. — Green on upper surface, grey on under surface. Average Dimensions of a Mature Specimen. Length, 35 mm. ; breadth, lo mm. ; girth, 24 mm. May be sought during the months of June to October. The Growth is complete by the end of August. These most interesting galls do not appear to be common ; they are very local where they occur. The affected leaves are situated on the new wood of the year. They are attacked while expanding ; and instead of opening out into a flat blade, the primary offshoots from the mid-rib are caused to remain as nearly parallel as possible with it, and the areas which they enclose are pushed upwards, giving both sides of the leaf a deeply striated appearance. They continue to grow in length, and ultimately bend inwards, assuming a cymbiform shape. The edges of some meet and produce a pod-like growth. Owing to the excessive pilosity they are like velvet to the touch. The illustration is of specimens gathered at Hastings by the author. 176 Plate 72. L.i;a\i;s or /-agt/s sy/rui/u: Monochetus sulcatus Nal. (FOUR-FIFTHS NAT. SIZE.) To face page lyS. Phyllocoptes acericola Nal. PLATE 73. Galls caused by the larvae, nymphs, and imagines of Phyllocoptes acericola Nal. on a leaf of Acer pseudo-platanns Linn. PLATE 73. Synonymy of Mite. Volvulifex aceris Amer. Ceratoneon vulgare Bremi. Phytoptus aceris Mur. Habitat of the Sycamore.— Distributed throughout Britain in gardens, private grounds, plantations, and parks. Position of the Galls. — On the upper surface of the leaf Manner of Growth. — Gregarious ; glabrous ; glossy ; more or less globular. Colour. — Orange -yellow, bright carmine, purple. Average Dimensions of a Mature Specimen. Height, 2 mm. ; girth, 3 mm. May be sought during the months of June to October. The Growth is complete by the end of August. These galls are well known to all who observe the sycamore- tree. They appear in very large numbers, sometimes so numerous as almost to cover the leaf It is not unusual to find as many as 650 on a leaf of average size. What may be lacking as regards size, is partly supplied by their excessive abundance, but mostly by the brilliancy of their colouring. A section of a gall seen under magnification shows the interior well filled with long hairs, amongst which the mites swarm in large numbers. The gall is also figured by Murray, " Economic Entomology," P- 357- The illustration is of a specimen gathered at Hastings by the author. 178 Plate 73. VF OF Aa'r psetido-platanus L Phylloioptes acerkola Nal. Phyllocoptes fraxini Nalepa. PLATE 74. Galls caused by the larvae, nymphs, and imagines of Phyllocoptes fraxini Nal. on the leaves of Fraxinus excelsior Linn. PLATE 7 J,. Synonymy of Mite. Phytocoptes fraxifii Nal. Habitat of the Common Ash.— Common in woods, thickets, plantation.s, etc., in dry or damp places, and often in hedges near woods. Distributed very generally throughout Britain. Position of the Galls. — The edges of the leaflets. Manner of Growth. — The edge of the leaflet curls down- wards and under, the opposite edges meeting at the mid-rib. Colour. — Very pale green with purple blotches, ultimately chocolate-brown. Average Dimensions of a Mature Specimen (a single roll). Length, 20 mm. ; breadth, 4 mm. May be sought during the months of June to October. The Growth is complete by the end of August. The specimen in the centre of the illustration shows the upper surface of the leaflets ; those on either side the under surfaces. At the left-hand side will be observed one leaflet in which both edges have curled and met at the mid-rib ; it is, however, more usual for only one-half of the leaflet to be rolled. The rolling is very irregular. The ends are open, and other minute creatures find a refuge within, a fact which may have caused these rolls to be labelled, in a public collection of specimens, as " the gall-nidus of Tettigonia ? — sp" These galls are often found in company with those caused by Diplosis botularia. The illustration is of specimens gathered at Hastings by the author. Plate 74. Leaves of /''mxiiii/s cxichinr Linn. Phyllocoptes fraxiiii Nal. (TWO-THIRUS NAT. SEZF..I To face page i8o. PLATE 75. Eriophyes tristratus, var. erinea Nalepa. AULAX GLECHOM^ Htg, PLATE 75. A. Leaflets of Juglans regia Linn. (Four-fifths nat. size.) Galled by Eriophyes tristratus, var. erinea Nal. Fig. I. Upper surface of five leaflets, showing eleven convexo-concave swellings. Fig. 2. Under surface of one leaflet, showing pubescence in three convexo-concave swellings. Fig. 3. Transverse section of one convexo-concave swelling See also plate 70. B. Stems and leaves of Glechoma hederacea Linn. (Nat. size.) Galled by Aulax glechomae Htg. Fig. I. Section of gall, showing larval chambers. „ 2. An old gall, showing holes through which imagines have emerged. Fig. 3. A very fine specimen, showing coalescence and entire absorption of the leaf. Presented by Mr. G. C. Walton, Folkestone. See also plate 109. The illustration is of specimens gathered at Hastings by the author. Platk 75. 2. B. A. Leaflkts of Juglans nxni Linn. (FOUR-FIFTIIS NAT. SIZE.) !. Lf,.\vi:s of Gkchoma hederacea Linn. (SAT. SIZE.) To face page 182. PLATE 76. Eriophyes