HESSIAN FLY. 
17 
About three hours after being first noticed the abdomen, as seen 
with a 1-inch power, was of various tints of a yellow-brown colour.* 
The following morning, on investigation of details, the thorax was 
black above, yellow or pale yellowish brown beneath the root of the 
wing, and with another patch of the same colour in front,—that is to 
say, a patch about half-way down on each side of the prothorax. The 
six segments of the abdomen nearest the thorax of a raspberry colour, 
paler below, with a broad black transverse band extending over the 
back and half-way down the side of each segment, which was also 
marked with a well-defined black velvety patch on each side. The 
terminal segments of the abdomen and the extended ovipositor were 
of nearly the same shade of yellow, or pale yellowish brown, as the 
patches on the side of the fore body, and the ovipositor was not 
furnished with lamellulie at the extremity. The 7th and part of the 
8th segments were marked above with a small V-shaped figure with a 
fine line on each side, parallel to the sides of the V, the lowest end of 
the V pointing backwards. The figure was only noticeable when the 
abdomen was seen from above, and was not of deep tint. 
The halteres or poisers were of a bluntly-pointed club-shape at the 
extremity, and yellow with a sprinkling of hairs, which in some lights 
gave a blackish tint to the upper part and also to the base of the club, 
and at this stage there was a marking of raspberry-red just about the 
middle of the poisers. The body and abdomen were in parts very 
hairy, and the black velvety patches on the sides of the abdomen 
appeared .to be composed of stout, black, bristle-like hairs. The two 
wings smoky-grey, fringed at the edges with long fine hairs, and 
sprinkled over the surface with hairs, and also with ribbed scales, 
resembling one of the forms found on butterflies’ wings. The wing- 
veins all ran lengthwise, the first almost close to the front margin of 
the wing, running parallel to it, and uniting with it about half-way 
down; the second running straight along the wing at rather less than 
one-third 'of the whole v/idth of the wing from the front, until near its 
termination at the tip of the wing it curved slightly backwards ; the 
third vein (placed about the width above mentioned from the hinder 
margin) runs almost straight, ending at the hinder margin about one- 
quarter of the length of the wing from its tip ; this third vein throws 
out a side-branch, which curves backwards to the hinder margin of 
the wing exactly opposite the termination of the first vein. Legs 
very long and fine, yellowish brown, hairy; uppermost joint of tarsi 
very short. Eyes black ; antennae beaded, long, and hairy. The two 
basal joints shorter and wider than the succeeding beads. The 
* For fuller descriptions than I can give from my own observations of the 
early changes of colour the reader is referred to Dr. Wagner’s paper, previously 
referred to. 
c 
