TEXT-BOOK OF ENTOMOLOGY 



The females, owing to their parasitic life, retain the larval form, 

 while the free males are winged, not leading in the adult stage a 

 parasitic life, though passing their larval and pupal stages in the 

 body of their host, and are so unlike ordinary beetles as to be 

 referred by good authorities to a distinct order (Strepsiptera). 



The triungulin stage of these insects corresponds in general to the 

 form of the larval Staphylinidse and allied families, such as the 

 Tenebrionidae, which are active in their habits, running about and 

 obtaining their food in a haphazard way, often necessarily suffering 

 long fasts. In the external-feeding, less active coleopterous larvae, 

 like the phytophagous species, which have an uninterrupted supply 



FIG. 645 Stylops childreni, tf : a, abdomen of Andrena with ? Stylops (6). 



of nutritious food, we see that the body is thick and fleshy. So also 

 in the larvae of the Scarabaeidae, Ptinidae, and the wood-boring groups. 

 In internal feeders, like the larval weevils and Scolytidae, which live 

 nearly motionless in seeds, fruits, and the sap-wood of plants and 

 trees, with a constant supply of nourishing, often rich food, the cru- 

 ciform body is soft, thick, and more or less oval-cylindrical. So it is 

 with the larvae of Hymenoptera, especially in the parasitic forms, 

 and in the ants, wasps, and bees, which are nearly if not quite 

 motionless, at least not walking about after their food. 



Now the change from the active triungulin stage to the series of 

 secondary, nearly legless, sedentary, inactive stages is plainly enough 

 due to the change of station and to the change of food. From being 

 an independent, active, roving triungulin, the young insect becomes 

 a lodger or boarder, fed at the expense of its host, and the lack of 

 bodily exertion, coupled with the presence of more liquid food than 



