LIFE-HISTORY OF PLATYGASTER 



701 



Certain ichneumons also appear to have two distinct larval stages, 

 as Ratzeburg inferred that in Anomalon there are four larval stages 

 (Fig. 648). 



In another ichneumon, Klapalek 

 detected what he calls the " sub- 

 nymph." The insect pupates within 

 the case of a caddis-fly, Silo (Fig. 649). 



In the Proctotrypidae there is also a 

 hypermetamorphosis, though the re- 

 markable precocious stages they pass 

 through are rather embryonic than 

 larval. 



In a species of Platygaster which is 

 parasitic in the larva of Cecidomia, the 

 first larva (Cyclops stage) is of a re- 

 markable shape, not like an insect, but 

 rudely resembling a parasitic Copepod 

 crustacean. In this condition it clings 

 to the inside of its host by means of 

 its hook-like jaws, moving about, as 

 Ganin says, like a Cestodes embryo 

 with its well-known six hooks. In 

 this stage it has no nervous, vascular, 

 or respiratory system, and the diges- 

 tive canal is a blind one (Fig. 651). 



After moulting, the insect entirely 

 changes its form ; it is thick oval- 



B 



FIG. 648. History of Anomalon 

 circumflexum : A, 1st instar or stage. 

 , 2d instar. C, larva in the 3d or en- 

 cysted stage removed from its cyst. />, 

 mature larva. E, pupa. After Ratze- 

 burg, from Sharp. 



FIG. 649. Metamorphosis of Agriotypus : A, larva. _B, "subnymph." C, case of the Silo, 

 with the string of attachment formed by Agriotypus. />, section of the case : v l , operculum of case ; 

 c 2 , cocoon ; ag, pupa of Agriotypus ; e, exuvia of same ; to 2 , wall of cocoon ; , remains of Silo ; w 1 , 

 Closure of case. After Klapalek, from Sharp. 



