CYNIPID^E. 



[ 228 ] 



CYNIPID^E. 



forms a channel, in which is lodged the very 

 delicate ovipositor. This organ, the con- 

 struction of which has been the subject of 

 some controversy, consists, as pointed out 

 by Westwood, of the same parts as that 

 of the ordinary parasitic Hymenoptera 

 (Ichneumonidce, Chalcididte, &c. ), namely, of 

 a superior bristle, channelled beneath, and 

 of two finer inferior bristles, which are re- 

 ceived into the channel of the former. 

 Although this ovipositor is not exserted, it 

 is of great length, reaching up to the base 

 of the abdomen in a subspiral curve ; it is 

 enclosed at its base between two broad 

 plates, representing the basal joints of the 

 bivalvular sheath of the ovipositor in other 

 Hymenoptera ; and the slender second j oints 

 of these valves accompany it to the apex of 

 the abdomen. All these parts are concealed 

 within the walls of the abdomen (PI. 36. 

 tig. 15). 



Although placed from their organization 

 in the same section of the Hymenoptera 

 as the parasitic Ichneumonidae, most of 

 the Cynipidae feed upon vegetable sub- 

 stances in the larva-state. The females 

 bore with their ovipositor into the tissues of 

 plants and trees, and there deposit their 

 eggs, from which small footless larvae are 

 produced. The irritation caused by the 

 injury thus done to the tissues, gives rise 

 to a morbid action in the part of the plant j 

 attacked, which is thus incited to grow ! 

 out into an excrescence varying in size, 

 form, and structure according to the specific 

 nature of the plant, the part of the plant 

 upon which, and the parasite by which, 

 the wound has been inflicted. Thus the 

 oak, which, of all our native trees, is most 

 infested by Cynipidae, furnishes nourish- 

 ment to upwards of a dozen species, which 

 attack all parts of it, from the leaves and 

 flower-buds to the root, and each of which 

 confines its operations to a particular por- 

 tion of the tree, and gives rise to a pecu- 

 liar excrescence. These morbid growths 

 are commonly known as galk, and the 

 insects producing them as Gall-flies; the 

 family, also, is called GallicolcB by some 

 authors. The larvae feed in the interior of 

 the galls ; those of some species are solitary, 

 whilst of others numerous individuals may 

 be found in the same gall, according as the 

 parent insect has deposited one or more 

 eggs in the same spot. When full-grown, 

 the larvae usually undergo their transforma- 

 tions within^the gall ; but in some instances 

 they eat their way out, bury themselves in 



the ground, and there pass to the pupa-state. 

 The larvae are liable to be attacked by 

 species of parasitic Hymenoptera, especially 

 the long-tailed Chalcididse (such as Calli- 

 mome, PI. 36. fig. 14) ; these pierce through 

 the substance of the gall and deposit their 

 eggs in or upon the Cynipidous larvae, 

 which are subsequently devoured by those 

 hatched from the eggs of the parasite. 



The recent elaborate researches of Adler 

 show that the Cynipidae exhibit the phe- 

 nomena of parthenogenesis, and that they 

 are dimorphic. Thus, in some broods, 

 both sexes are present ; while in others, fe- 

 males only are produced. The members of 

 the two broods are quite dissimilar, and 

 have been regarded as constituting diffe- 

 rent genera ; the galls they produce are also 

 different. These observations serve to solve 

 the mystery existing some years ago as to 

 the non- occurrence of males among large 

 broods of Cynips. He also states that the 

 reproductive organs in the two kinds of 

 broods are very similar ; and that there is a 

 rudimentary receptaculum seminis in the 

 agamic generations. 



The tissues of the galls are sometimes 

 soft and juicy, sometimes hard and woody ; 

 in the latter case the woody tissue lies im- 

 mediately beneath the skin, and within it 

 is a layer of cellular tissue filled with 

 starch-grains. These galls are usually 

 formed on branches or twigs. One of the 

 most remarkable of them is the Bedeguar 

 gall of the wild rose, which is produced by 

 the puncture of Rhodites Rosa (PI. 36. fig. 

 16) : it is a large gall entirely covered with 

 compound bristles, like those of the moss- 

 rose, which give it the appearance of a 

 ball of moss ; in its interior are numerous 

 cells, each of which serves as a habitation 

 for a larva ; and the whole is produced at 

 the extremity of a shoot of the wild rose, 

 upon which the female gall-fly deposits 

 numerous eggs. 



The Cherry-gall of the oak-leaf is pro- 

 duced by Cynips folii (fig. 17), one of the 

 commonest of our native species ; and an- 

 other gall-fly, Teras terminalis (fig. 18), by 

 attacking the young shoots of the oak, gives 

 origin to the well-known oak-apples. The 

 leaves of the oak are also attacked by at 

 least two so-called species of the genus 

 Neuroterw, which really consists of the 

 parthenogenetic brood of Spathegaster, the 

 punctures of which give rise to small, flat, 

 rounded galls, attached to the leaf only by a 

 small portion of their lower surface, and 



