DIPTERA. 
99 
wood. “The wart-like galls common on the meadow¬ 
sweet ( Spiraea); the uneven swellings on the stalks and 
leaves of the stinging-nettle ; the little furry purses on 
the ground-ivy ; the woody, shapeless excrescences on 
the raspberry plants ; the slender upright growth on 
beech leaves ; the blisters on bed straw, yellow nettle, 
and others ; the knots within the very blossoms of many 
flowers—all these, and a great many more, are the work 
of little creatures in this numerous family” (Staveley). 
On Plate IV. (Fig. 1) will be seen a magnified drawing 
of the Wheat-midge ( Cecidomyia tritici ), the larvae of 
which occasionally do much mischief to the wheat crops. 
This insect is a near relative of the Hessian-fly, the North 
American scourge, whose ravages have even caused 
famine in the land. The larva) of the Wheat-midge 
feed on the flower of the wheat, rendering it abortive. 
The eggs are laid in June, the larvae changing to pupae 
upon the sound grains and inner valves, or entering the 
ground for that purpose, the perfect insects hatching in 
the summer. 
The Bibionidcu I have represented on Plate IV., Fig. 8, 
by the well-known Bibio Marti , the Hawthorn-fly of the 
angler, whose deep black bodies and white wings of the 
male, and long legs pointing backwards, must be familiar 
to the most unobservant. The larvae feed on the roots 
of grass ; they are worm-like and cylindrical, with 
transverse rows of short hairs, serving for locomotion ; 
the pupae are naked, enclosed in a smooth oval cell. 
The perfect insect appears towards the end of April, 
about St. Mark’s day, hence the specific name of the 
insect Marti . 
The Simulida ?, Chironomydce , and Culicidce , are emi- 
