80 



NATURAL HISTORY, 



FAMILY V.-CECIDOMYIDJE. 



The Cecidomyidae, or GALL MIDGES, constitute the last family of Gnat-like Diptera, and are indeed 

 the most frail and delicate of all. They have a slender and elongated form ; very long, necklace-like 

 antennae, composed of not less than thirteen joints, but usually of many more, in some cases as many 

 as thirty-six, and each joint bears a circlet of short hairs ; very long, slender legs, of which the tibiae 

 are not armed with spines, and the first joint of the tai'si is minute ; and wings with very few simple 

 veins. The eyes are lunate or notched in front towards the insertion of the antennae. There are no 

 ocelli ; and the palpi are four-jointed and of moderate length. The females usually have a long 

 ovipositor. 



The larvae of these elegant little insects feed upon various species of plants, generally in gall-like 

 excrescences or distortions of the parts inhabited by them, and the different species attack different 

 parts of the plants they infest ; and in all these respects, as Professor Westwood suggests, as well as in 

 their generally minute size and comparatively veinless wings, these insects present a striking analogy 

 to the true Hymenopterous Gall Flies. The larvae, which are of a stouter and more ovate form than 

 in the preceding families, live within the part of the plant which furnishes their nourishment, which 

 may be the young shoots, the leaves, or even the flowers, and the part thus attacked either swells into 

 a regular gall, or becomes distorted in various ways. The number of species is very considerable, about 

 100 being recorded as inhabiting Europe. Many of them, by attacking useful plants, frequently do 

 much mischief. Among these may be mentioned especially the HESSIAN FLY (Cecidomyia destructor), 

 which has done so much damage to the grain-crops in the United States of America, and i-eceived its 

 vernacular name from a belief that it was introduced into the States with the baggage brought by 

 Hessian troops in the pay of the English Government about the year 1776, for which, however, there 

 appears to be no foundation. This redoubtable fly averages rather more than an eighth of an inch 

 in length, and is of a black colour, with some parts, such as the under surface of the abdomen, red. 

 The female has a well-developed ovipositor. The flies begin to make their appearance in April, and 

 continue emerging for four or five weeks. After pairing, the female sets to work to deposit her eggs, 

 which number from 80 to 100, placing them singly, or two or three together, upon the leaves 

 of the wheat-plants. The larvae are soon hatched out, when they make their way down the leaf and 

 take up their abode within its sheath. Eight or nine larvae may be found associated in this situation, 

 and their effect upon the plant is to weaken the haulm, so that in the first place the ear is not so 

 well nourished as it should be ; and in the second, when the ear is filled out the haulm is not 



able to bear its weight, but 

 easily gives way under the 

 pressure of the winds. These 

 formidable larvae seem to a 

 certain extent to combine the 

 characters of the ordinary 

 larva of the Nemocera with 

 those of the maggots of flies. 

 They are virtually headless, 

 but have their stigmata placed 

 upon the sides of the seg- 

 ments of the body. This cha- 

 racter is common to the rest 

 of the larvae of the family, in 

 many species of which we also 

 find another approach to the 

 Athericerous Flies, namely, 

 that they do not cast the 

 larva-skin before passing to 

 the pupa state. Hence the pupae of the Hessian Fly are known as the "flax-seed state" of the insect. 

 The perfect insects of the first brood emerge about the end of August, and these deposit their eggs 



A, LARVjF, OF AVHEAT MIDGE (Ceddomyia trititi) IN FLOWER OF WHEAT ; B, LARVA 

 ATTACHED TO GRAIN OF WHEAT ; C, LARVA ; D, PERFECT INSECT. 



