THE CECIDOMYIDZ. 395 
living larvee within it (after Wagner). In the spring-time the little 
perfect insect lays its eggs, and by-and-by the larve are hatched 
from them. If these larvae are examined, smaller ones will be 
noticed inside them, and eventually they tear open the body of 
their mother and escape. They reproduce others in the same 
fashion, and a succession of these extraordinary generations takes 
place during the whole of the fine weather. The increase of these 
larvae progresses at a great ratio, and finally metamorphosis takes 
place when the cold weather is at hand. This curious parthe- 
nogenesis (from the larva, not from the perfect insect) has been 
carefully studied by excellent observers, and is an established fact. 
An equally interesting development from immature insects occurs 
in the case of the larve of Chivonomus, which have been proved 
by a Russian naturalist to contain eggs which are subsequently 
laid by the pupe. The gall-making species are usually very small 
as regards their individuals, and the females deposit their eggs in 
the young shoots, leaves, or flowers, which they pierce by means 
of their sharp-pointed ovipositor. Where this puncture is made a 
gall or excrescence takes place, which grows sometimes to a large 
size, serving often as a nest and food to the young larve. 
The Asclid@ belong to the second division of the Dzptera, and 
are very active insects, which have a very formidable sucker, for 
the two mandibles being completely soldered together form a 
very sharp and piercing blade. The species are very numerous, 
and are strong predatory insects, living upon live flies, and even 
upon bees, which they chase and soon kill. Their flight is strong, 
and they make a loud buzzing noise when on the wing. Some, 
which have elongated bodies, a short trunk, and a formidable 
sucker, attack horses and cattle, and sometimes man, and they 
pierce the skin and suck the blood. One of the commonest 
European species, Asilus crabroniformis, is decorated like some 
of the Hymenoptera, and when it begins to suck produces the 
same pain as that inflicted by a sharp lancet. It often attacks 
large animals, but usually it sucks the blood of insects, and 
especially of caterpillars. 
This insect, which is so bloodthirsty in adult age, appears to 
be a vegetarian when in the condition of a larva. The larvae 
are found underground, where they gnaw roots, and eventually 
