Wasps 



which the larva, after hatching, can thrust its head, or which it 

 can at least enlarge easily so as to insert its head. The egg is 

 oval, soft, translucent, about a third of a millimeter long, apparently 

 has no peduncle, and is not very firmly attached to the skin of the 

 dermestid. From one to six eggs are laid upon a single victim. 

 In a few days the larvae hatch, yellow in color and very indistinctly 

 jointed. Immediately on hatching, their mouths are closely ap- 

 plied to the skin of 

 the paralyzed der- 

 mestid and they be- 

 gin to grow, not so 

 rapidly as the some- 

 what similar Eu- 

 plectrus, which will 

 be described in a 

 succeedingchapter, 

 but still rather rap- 

 idly, reaching full 

 growth in from ten 

 to fourteen days. 

 When full grown, 

 a group of these 

 larvae with their 

 heads inserted at 

 a central point, look not unlike the petals of a curious 

 flower growing out of the shriveled dermestid larva. When 

 only one Laelius larva occurs upon a host it sometimes enters the 

 sucked-dry skin and spins its cocoon within it, but generally the 

 white, rather loose, silken cocoons are spun outside the skin of the 

 dermestid, which shows large holes where the parasitic larvae have 

 been at work. After the cocoon is formed the larva remains within 

 it, motionless, for ten days or more, finally transforming to a white 

 pupa with red eyes. This white color changes gradually to black 

 and in eight to ten days further the adult fly issues from the end 

 of the cocoon through a ragged hole. The entire life duration of 

 a generation, in the summer-time, is from thirty to thirty-five 

 days and the insect passes the winter as a larva in its cocoon, the 

 cocoons of the winter generation being firmer than those of the 

 summer brood and darker in color. Mr. Busck observed that a 

 female will paralyze all dermestid larvae with which it comes in 



35 



Fig. 1 8. Leelius trogodermatis : dermestid larva 

 at right, showing eggs of parasite; full- 

 grown parasite larvae at left ; adult 

 parasite in centre (original). 



