336 PARASITISM 



larva is of a typical, active, campodeiform type. Thus, in certain 

 species of the Staphylinid genus Aleochara the primary larva is 

 engaged in seeking out Anthomyiid puparia, and having discovered 

 its host, it bores its way within and transforms into an inert 

 cruciform parasite, its obvious degeneration being correlated with 

 the changed mode of life {vide Wadsworth, 1915 ; Kemner, 1926 ; 

 Voris, 1934). Silvestri (1904) has shown that the Carabid Lebia 

 scapularis, whose host is the Chrysomelid beetle Galerucella 

 luteola, passes through a very similar type of hypermetamorphosis. 



The triangulin or first stage larva so characteristic of the order 

 Strepsiptera, and present also in the Meloidae and Rhipiphoridse 

 among Coleoptera, is comparable with the campodeiform larva 

 of Aleochara and Lebia just alluded to, and entomologists are 

 familiar with the campodeiform primary larva of Mantispa 

 among Neuroptera. There is little doubt that in these examples 

 the first stage larva is the primitive one, and the adoption of a 

 parasitic mode of life is responsible for the highly modified instars 

 that supervene. Comparison with the ontogeny of members 

 of allied families which lead a normal non-parasitic existence 

 supports this contention. It is noteworthy that the general 

 similarity, both in structure and behaviour, of the Hymenopterous 

 planidium and these campodeiform primary larvns has been 

 commented upon by several observers. Wheeler is inclined to 

 pursue the analogy further and to regard the planidium as an 

 archaic, though often considerably modified stage which has been 

 suppressed in other families of Hymenoptera. In the Tachinid 

 Diptera, however, evidence points to the migratory phase being 

 an adaptive one secondaril3^ intercalated in the ontogeny. 



3. Non-migratory Primary Larvae. This habit appears to be 

 infrequent, but prevails among certain members of the Tachinidse 

 which betray leaf oviposition. It is probable that true larvi- 

 position does not occur, as has been sometimes stated, but that 

 the larvae issue from the eggs almost immediately after the 

 latter have been laid. The behaviour of Bonnetia compta 

 (Strickland, 1923) and of Ernesiia (Panzeria) rudis (Prell, 1915) 

 which parasitise caterpillars, may be regarded as typical. 

 Oviposition occurs on the food-plants of the host, and the young 



