286 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 3 



the bottom of the box and crawling about until they strike a corner, by 

 means of vigorous efforts with the mouth hook and muscular con- 

 tractions of the powerful body, they will often manage to make a 

 small hole through cardboard of considerable thickness and escape. 

 Under such circumstances, a maggot is able to force itself through 

 an opening so small that if an effort be made to remove it forcibly 

 when it is part way out, the death of the parasite will generally 

 result, although left to itself it can work through successfully. This 

 propensity of the maggot to burrow downward and seek the earth 

 has been utilized in a device, the invention of Mr. "W. F. Fiske, for 

 handling pupa? of the gipsy moth which contain the maggots of 

 Blepharipa or Crossocosmia. These are placed upon a piece of 

 mosquito netting stretched over a cylinder of earth into which it is 

 desired that the maggots shall pupate, and through which they descend 

 upon emerging from the host pupai, falling upon the earth and at 

 once entering it to pupate. A small cylindrical wire screen cage 

 tightly fitting within the top of the cylinder containing the earth 

 catches the moths and any summer-issuing parasites as they emerge. 

 When it is certain that no more parasites will emerge the cylinder is 

 covered up and buried in some moist cool spot after which it needs no 

 further attention until spring. 



In the experiment with the larvae of Blepharipa cited above, it was 

 noted that the larv^ffi which were placed upon earth, after descending 

 for a few inches, turned about and proceeded to pupate with the 

 anterior end directed upward. This position of the puparium has 

 been observed at the laboratory in connection with other Tachinids, 

 and also with ]\Iuscids and Sarcophagids and is very probably the 

 usual mode of pupation among those species of Calyptrate Muscids 

 which form their puparia in the soil. It is, of course, designed to 

 facilitate the emergence of the fly from the earth in the spring, as the 

 latter reaches the surface by the alternate expansion and contraction 

 of the ptilinum, that organ being provided with many back^^'ardly 

 directed spines which serve to draw the fly upward through the 

 earth. 



Pupation of Tachinids of the second class. The Tachinid para- 

 sites of the second class have presented themselves much more fre- 

 quently in our work than those of the first class, and they are un- 

 doubtedly of more general occurrence. They may be sub-di\aded as 

 follows: (1) Those with a long pupal period; (2) Those with a short 

 pupal period. The first group includes those forms which having but 

 a single generation annually, hibernate in the pupal stage, but there 

 must also be included in it those species of the second sub-division 



