NATURAL ENEMIES 91 



both sexes crawled rapidly. The female is able to fly ; 

 but the favorite mode of locomotion appears to be 

 crawling. The wings of the male appear to be non- 

 functional. Actual experimentation with fifty maggots 

 and ten puparia of the house fly showed that the para- 

 sites laid their eggs in the puparia and developed rap- 

 idly. The maggots and puparia were placed in a breed- 

 ing jar on September 9th, and on September 26th six 

 males and ten females of the parasites issued from the 

 puparia. On September 12th, eight female parasites 

 were confined separately in small gelatine capsules, 

 each with a healthy puparium of the house fly. The 

 parasites appeared to lay their eggs in several cases, 

 but none issued afterwards and about half of the flies 

 came out. 



Most careful observations were made by the authors 

 on the egg-laying process of this parasite. The female 

 was observed to walk carefully over a two-days' old 

 puparium, examining the entire surface. After a point 

 was selected, the ovipositor was inserted with some dif- 

 ficulty, the operation requiring one minute and a half. 

 The hole was then enlarged, and the ovipositor was 

 again pushed in for its entire length and remained for 

 forty-five seconds, during which time apparently an 

 egg was deposited. After the ovipositor was with- 

 drawn the parasite examined the puncture with its 

 antennae and mandibles. 



The parasite apparently attacks only the puparium, 

 and that only after it has been formed for about twenty- 

 four hours, and a number of them issue from the same 



