REPORT OF THE ENTOMOLOGIST. 535 



it belongs has not been worked up and because the characters are not 

 well understood. 



Tacliina flies are very easily overlooked, because they resemble 

 large house-flies both in appearance and flight, and their presence 

 out of doors is not usually noticed on that account. Yet they play 

 a very important role, living as they do in their larval state entirely 

 in insects. During the caterpillar plague such flies were often seen 

 to dart repeatedly at an intended victim, buzz about it, and quickly 

 disappear. If the caterpillar thus attacked was investigated, from 1 

 to 4 yellowish- white, ovoid, polished, and tough eggs would be found 

 usually fastened upon its neck, or on some spot where they could 

 not readily be removed. These eggs are glued so tightly to the skin 

 of the caterpillar tliat they cannot easily be removed. Sometimes as 

 many as 7 eggs could be counted upon a single caterpillar, show- 

 ing 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 vic- 

 tim happens to be near a molt, it casts its skin with the eggs, and es- 

 capes a sdow but sure death. But usually the eggs hatch so soon.that 

 the small maggots have time to enter the body of the caterpillar, 

 Avhere 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, tunlike object (known technically as the co- 

 arctate pupa), which contains the true pupa. The cateri:)illar, tor- 

 mented 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 prevalence 

 of the caterpillars, but it is impossible to state positively whether 

 they were all bred from them or not, since the many species of this 

 genus of flies resemble each other so closely, that a very scrutinizing 

 investigation would have been necessary to settle such a question. 

 But there is no doubt that they were very numerous during the sum- 

 mer. Some maggots obtained from caterj)illars kept for this pur- 

 pose in breeding jars changed to flies in six days, others appeared in 

 twenty-three days, and still others, obtained at about the same time, 

 are still under ground, where they will hibernate. The maggots of 

 these flies do not, however, always enter the ground, as some were 

 found inside cocoons made by caterpillars among rubbish above 

 ground. 



REMEDIES. 



Pruning and Burning. — The old and well-tried remedies of prun- 

 ing or burning, or pruning and burning, will answer every purpose 

 against this insect in ordinary seasons, where it is thoroughly done 

 and over a whole neighborhood. It must, however, be done upon the 

 first appearance of the webs on the trees, and not, as was done by 

 the Parking Commission of this city last season, after the first brood 

 of worms had attained their full growth and many had already trans- 

 formed to pupse. The nests at that time had assumed large propor- 

 tions, and their removal entire injured the appearance of man;^ young 

 trees. Then, too, they were piled upon an open wagon, which was 

 dragged for many hours around the streets, permitting a large pro- 

 portion of the worms to escape. 



On the first appearance of the webs, which should be looked for 



