OVIPOSIT ION 339 



little developed in some forms and more evident in others. In 

 the Chalcid genera Eupelmus, Eurytomus, Torymus and Leucospis, 

 bands of slender macrochaeta^ are very characteristic. The 

 foregoing characters disappear in the later instars and finally 

 there remain few or no evident structural differences whereby 

 an ectoparasite can be distinguished from the later instars of 

 most endoparasites. This subject is also discussed by Evans 

 (1933) with reference to certain Hymenopterous parasites of 

 Diptera. 



Group C. External oviposition or larviposition, followed by an 

 endoparasitic life, is exemplified in many Tachinidae which form 

 Groups I., III. and VI. of Pantel (1909). 



In Pantel's Group I. those Tachinids with a macrotype egg 

 {i.e., relatively large and of a short, somewhat flattened form) 

 oviposit on the bodies of the hosts, fastening the eggs in position 

 by means of a glutinous secretion. 

 The embryos in such eggs are but 

 little developed at the time of 

 oviposition, and are covered with 

 a tough, durable chorion. Emer- Fig. 80. Empty egg (e) of T/^rmon 

 gence from the eggs may take ^:S^%^^^^„t 

 place in one of two ways. Either shown the passage eaten by the 



the chorion dehisces, but aids in }^^^^ JT ^^ff""^ ^^'^ host. 

 ' ^ _ (From Pantel.) 



maintaining the larva in position as 



it bores its way through the integument of the host ( Winthemyia 

 4<-pustulata and Tricholyga major) ; or, the chorion does not 

 rupture and the larva eats its way through that part of it which 

 is in contact with the integument of the host, entering the latter 

 without exposure to the exterior (species of Tachina, Gymnosoma, 

 Thrixion (Fig. 80), Centeter, etc.). In Centeter cinerea Clausen and 

 his co-workers (Fig. 78) mention that the eggs are laid on the 

 hard integument of the Japanese beetle, and the first instar 

 larva has its mouth-parts armed with a dentate rasper ^ which 

 enables it to bore through the cuticle of the host. Owing to errors 

 of the oviposition instinct, many larvae perish on account of the 



1 This structure is frequently present in larvae which bore through the 

 integument of the host- 



