500 HOMES WITHOUT HANDS. 



which have made their cells in the above-mentioned cocoon be- 

 long to the species called Paniscus glaucopterus, and are of a yel- 

 lowish hue. It sometimes happens that the insects fail in making 

 their way through the cell walls and die in the interior. This ac- 

 cident, however, seems chiefly to befall the ichneumons produced 

 in cocoons which are kept in houses for the purpose of breeding 

 the Puss Moth, and which are, in consequence, harder and more 

 dry than those which remain in the open air, adhering to the 

 trunks of trees. 



Those splendid insects which are popularly called Ruby-tail- 

 ed Flies, or Firetails, and scientifically are termed Chrysididce, 

 are also to be numbered among the parasitic insects. 



They make no nests for themselves, but intrude upon those of 

 various mason and mining bees, and several other insects. The 

 Firetail does not, however, lay its eggs in the body of the larva, 

 but makes its way into the nest while the rightful owner is ab- 

 sent, and places an egg near that of the bee. The egg of the par- 

 asite is sometimes hatched at the same time with that of the bee, 

 but generally later. In the first instance, the larva feeds on the 

 provisions which were supplied for the bee, and so starves the 

 poor creature to death ; and in the latter case, it is not hatched 

 until the young bee is large and fat, and capable of affording am- 

 ple subsistence to the parasite, which fastens upon it and devours 

 all the after portions. 



Then there are the Cuckoo Flies (Tachince), which bear some 

 resemblance to the common house-fly, but which are parasitic, 

 feeding on the larvee of other insects, and selecting the same spe- 

 cies which are persecuted by the firetails. When the Tachina 

 larva has eaten that of the mason bee, it forms an oval cocoon, 

 and there remains until the time for becoming a perfect insect. 

 A single larva of the mason bee seems to be sufficient for the 

 Tachina grub, as Mr. Rennie has recorded an instance where two 

 larvas of the mason bee were in a nest into which a single egg of 

 the Tachinse had been introduced. The parasitic larva devoured 

 one of the rightful inhabitants, but did not touch the other, and 

 the cocoons of the bee and the Tachina were formed side by side. 



Sometimes, as has already been mentioned, the chrysalis itself 

 of a lepidopterous insect becomes the home of the parasite. I 

 have found the pupae of various butterflies absolutely filled with 



