176 ENTOMOLOGY 



triungulin larvae issuing from a female Stylops in the body of 

 an Andrena. The further life history of Stylops is but im- 

 perfectly known; probably the triungulin climbs upon a bee 

 or a wasp and enters its body, after the manner of the Euro- 

 pean Rhipiphorus paradoxus, whose life-history is much bet- 

 ter understood. 



The most extraordinary metamorphoses have been found 

 among parasitic Hymenoptera, as in Platygaster, a proctotry- 

 pid which infests the larva of Cecidomyia. The egg oi'Platy- 

 gaster, according to Ganin, hatches into a larva of bizarre 



FIG. 218. 



mo 



Stages in the hypermetamorphosis of Platygaster. A, first larva; B, second larva; 

 C, third larva; a, antenna; b, brain; f, fat-tissue; h, hind intestine; m, mandible; mo, 

 mouth; ms, muscle; n, nerve cord; r, reproductive organ of one side; s, salivary 

 gland; t, trachea. After GANIN. 



form (Fig. 218, A), suggesting the crustacean Cyclops, rather 

 than an insect. This first larva has a blind food canal and no 

 nervous, circulatory or respiratory systems. After a moult 

 the outline is oval (B), and there are no appendages as yet, 

 though the nervous system is partially developed. Another 

 moult, and the third larva appears (C), elliptical in contour, 

 externally segmented, with tracheae and a pair of mandibles. 



