. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. 56 OUR SHADE TREES AND THEIR INSECT DEFOLIATORS. ber of them. But tlie Hy uow to be described is fully as useful as any of tbe others. "'Tachiua-flies are very easily overlooked, because they resemble large house-flies, both iu appearance and in flight, and their presence out of doors is not usually noticed on that account. Yet they play a very important role, living as the^^ do iu their larval state entirely iu insects. During the caterpillar plague such flies were often seen to dart repeatedly at an intend
. Bulletin. Insects; Insect pests; Entomology; Insects; Insect pests; Entomology. 56 OUR SHADE TREES AND THEIR INSECT DEFOLIATORS. ber of them. But tlie Hy uow to be described is fully as useful as any of tbe others. "'Tachiua-flies are very easily overlooked, because they resemble large house-flies, both iu appearance and in flight, and their presence out of doors is not usually noticed on that account. Yet they play a very important role, living as the^^ do iu their larval state entirely iu insects. During the caterpillar plague such flies were often seen to dart repeatedly at an intended victim, buzz about it, and quickly disai)pear. If the caterpillar thus attacked was investigated, from one to four yellowish-white, ovoid, polished, and tough eggs would be found, usually fastened upon its neck, or some spot where they could not readily be reached. These eggs are glued so tightly to the skin of the caterpillar that they can not easily be removed. Sometimes as many as seven eggs could be counted upon a single caterpillar, showing a faulty instinct of the fly or flies, because the victim is not large enough to furnish food for so many voracious maggots. If the victim happens to be near a molt, it casts its skin with the eggs and escapes a slow but sure death. But usually the eggs hatch so soon that the small maggots have time to enter the body of the caterpillar, where they soon reach their full growth, after which they force their way through the skin and drop to the ground, into which they enter to shrink into a brown, tun-like object (known technically as tbe coarctate pupa), which con- tains the true pupa. The caterpillar, tormented by enemies feeding^ within it, stops feeding and wanders about for a long time until it dies. As a rule not more than two maggots of this fly mature in their host, and generally but one. The caterpillar attacked by a Tachina-fly is always either fully grown or nearly so. "Tachina-flies abounded during the whole term of the
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