THE CECIDOMYIV^. 



31 



upon young plants of winter wheat. The larvse arrive at maturity and change to the pupa before 

 winter, which season they pass in the latter state. The Hessian Fly has made its appearance of 

 late years in Posen and other parts of Germany. 



The WHEAT MIDGE (Cecidomyia tritici) is an enemy of the wheat crops in England, and 

 sometimes does much damage. This little plague, however, attacks a very different part of the plant 

 from the Hessian Fly, the female, by means of her long ovipositor, introducing her eggs into the 

 heart of the blossom, sometimes to the number of twenty together. The larvse, which are of a yellow 

 or orange colour, are known by the name of the " Red Maggot," and seem to attack the central 

 organs of the flower, injuring them so that the seeds are unable to arrive at their full development 

 It was formerly supposed that they fed upon the pollen, but this does nob appear to be the case. 

 When full grown the larvse go down to the ground, where they undergo their change to the pupa 

 ctate. The perfect insect, which is about a tenth of an inch long, is of a yellow or orange colour,, 

 with black eyes. A second Wheat Midge is recorded as occurring in Britain under the name of 

 Lasioptera obfuscata. The perfect insect is of a black colour ; but the larvse and pupa are exactly 

 like those of C. tritici, 

 and the habits of the 

 two insects are identical. 



Of the actual galls 

 produced by these insects 

 the most striking form, 

 and one of the best 

 known, is that formed 

 upon several species of 

 willow. The fly attacks 

 the terminal shoots, 

 which are then stunted 

 in their development, 

 and are so changed in 

 character as to make a 

 flower-like body, com- 

 pared to a rose by some 

 of the older writers, who 

 regarded the willows 

 thus affected as a pecu- 

 liar species, which they 

 denominated the rose- 

 willow. The insect pro- 

 ducing this gall was even 



described under the name of Cecidomyia rosaria. A somewhat similar gall is produced by Cecidomyia 

 cratcegi and circumdata upon the hawthorn. Another species (C. veronicce) lives in hairy, gall-like 

 bodies on the germander speedwell. C. salicis forms woody galls on the twigs of willows, and 

 C. bursaria resides in pyramidal hairy galls on the leaves of the common ground-ivy. 



In 1860 a remarkable circumstance in the history of the Cecidomyidse was discovered by a Russian 

 naturalist, Dr. Nicolas Wagner, at that time Pi-ofessor in the University of Kasan. He found that 

 certain Cecidomyian larvse living under the bark of trees develop within them organs analogous or 

 homologous with ovaries, in the chambers of which young larvse are produced, and these, after 

 remaining for a time free in the general cavity of the parent larva, living and increasing at its 

 expense, at last break out of it, leaving nothing but the empty skin. These young larvae then 

 produce other larvse in the same curious fashion, and one generation succeeds another throughout 

 the autumn, winter, and spring. In the summer the last generation undergoes a change to the pupa 

 state, and from the pupa perfect males and females emerge ; the latter, after impregnation, deposit a 

 small number of eggs in the bark of trees, the larvse produced from which commence a fresh series 

 of agamic broods. These species have been referred to a distinct genus named Miastor. 

 249 



CECIDOMYID WITH VIVIPAROUS LARVA. 

 A, Adult Insect ; B, B, Pupa; ; c, Larva, showing young larvas at a a. 



