180 THE BRITISH NATURALIST. [August 



Insects. But the Hessian Fly was present before the great scare 

 of 1886, for, as mentioned in my work on British Flies (Diptera), 

 it was noticed by the founder and editor of the Entomologist 

 in 1876, ten years before the scare came. The opinion amongst 

 Dipterists is that the Cecidomyia destructor has always been a native of 

 our islands, and not, as was supposed, a recent introduction. The 

 Hessian Fly belongs to an order of insects known as Diptera, or 

 two-winged flies. 



If one of these pests that have been doing so much damage in South 

 Devon be examined we shall see that it possesses two wings only, and 

 that these are the front or anterior wings. Behind them we shall see a 

 pair of club-shaped processes or balancers ; these represent the posterior 

 pair of wings of the butterfly or bee. The Hessian Fly, then, is a true 

 dipterous insect. Now, amongst these Diptera we find a family known 

 as the Cecidomyadse, very small flies whose maggots or larvae 

 produce deformities or galls upon various kinds of trees and plants. 

 The pest we are dealing with does not, however, form a gall as a rule, 

 nor does its near ally, the Wheat Midge or Red-gum (Diplosis tritici), so 

 well-known to farmers ; but last year in Devon I noticed that galled 

 swellings were very prevalent where the maggots were present. . 



The perfect insect appears at two separate seasons of the year, the 

 first brood hatching in May and June, the second in August and 

 September, and a few even as late as October. The imago, or adult fly, 

 is brown with a pinkish or yellowish-brown abdomen. The antennae, 

 or horns, are yellowish-brown, and composed of 17 joints in the female, 

 and the same number in the male, but with longer joints ; they are 

 hairy in both sexes. The legs vary from pink to light-red. The wings 

 are covered by a downy pubescense and have very few veins in them, 

 the latter a character of the family to which destructor belongs. Both 

 male and female are very small, the former being about 2111m. in length, 

 the latter about 3mm. For a detailed description of this insect the 

 reader is referred to my work on British Flies (Diptera). t 



The female of the fly we are now considering generally lays her eggs 

 throughout May and June, upon the leaves of wheat and barley. The 

 eggs are small cylindrical bodies, rounded at each end, and of a pale orange 

 colour at first. The eggs hatch in four or five days. As many as 250 

 may be laid by a single female ; they are generally placed in batches of 

 eight or ten on separate leaves and plants. The newest leaves of the 

 plant are apparently always chosen for egg deposition, and the ova are 

 invariably placed with the head end downwards, so that the maggot 

 which springs from the egg can at once commence its passage down the 



* Curtis, " Farm Insects," 1859, p. 258. 



tTheobald. " An account of British Flies," 1892. Vol. I., p. 51. 



