THE TUBULIFERA. 249 



is far more applicable to those which must next engage 

 our attention. These are also parasitic in their habits, 

 but their larvae appear in many cases to feed, in the 

 first place, upon the store of nourishment laid up for 

 their victims, although they doubtless finish the bu- 

 siness by devouring their involuntary hosts. Most of 

 them pass the larval stage of their existence in the nests 

 of various species of solitary Bees and Wasps, and the 

 female exhibits the greatest assiduity in watching 

 these insects whilst engaged in the construction and 

 storing of their nests, in order to seize the proper 

 opportunity for stealing in and depositing its own 

 egg. Sometimes, however, the insect to whom this 

 favour is intended discovers the marauder, and drives 

 her away from the vicinity of their nests, and in one 

 instance, recorded by Saint Fargeau, a Bee (Mega- 

 chile muraria) finding a specimen of one of these 

 parasites lurking about her nest on her return loaded 

 with food for her progeny, seized upon it with her 

 jaws, bit off the wings of the intruder, and rolled it 

 to the ground. Even this exertion of instinct, how- 

 ever, was ineffectual, for the crippled parasite imme- 

 diately crawled up the wall to the Bee's nest, and 

 finding that the rightful owner waff gone in search of 

 a further supply of food, deposited an egg in the cell, 

 the larva hatched from which would doubtless fully 

 avenge the wrongs of its parent. 



There is probably a considerable difference in the 

 time in which the young larvae are evolved from the 

 eggs of different species of these Cuckoo-flies, as 

 their food appears in all cases to be of an animal 

 nature, and they are found in the nests of insects of 

 such different habits, as the solitary Bees and Wasps, 

 the former of which store their cells with honey and 



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