April, IDIS] Parasites of LeaJ-IIoppers 199 



As growth occurs, the second exuvium becomes spHt open 

 in the same manner as did the first, a fact coincident with a 

 third larval molt, and the third exuvium is pushed outward 

 by the larva, now in its fourth instar, exactly as before. The 

 fourth larval stage is not comparable to the other four. It is 

 characterized by the development of the m,andibles, beneath 

 which are formed those of the fifth stage. There is no complete 

 fourth molt, so far as is revealed by dissections, other than a 

 shedding of the head capsule. It is possible that this instar 

 is entirely eliminated in some of the more highly specialized 

 species. The larval sac has become of considerable size by now, 

 and is plainly visible on nymphs and brachypterous forms. 

 In winged species, the sac pushes one wing and elytron up out 

 of place. The host becomes very evidently affected by now, 

 being sluggish and easily caught. In from eighteen to nineteen 

 days after the appearance of the sac the fourth partial molt 

 occurs, and the larva enters upon its fifth and last larval instar. 

 Up until this time it has not touched any vital part of the host. 

 The mouth-parts of all the preceding instars are soft and slightly 

 chitinized, while in this last stage, sharp, heavily chitinized 

 mandibles are developed and the tissues of the host are 

 devoured. Growth is now very rapid, and soon the larva 

 breaks through the sac, first being seen as a narrow white band 

 between the slightly gaping halves of the exuviae. Peristaltic- 

 like movements take place spasmodically in the maggot, w^hich 

 increases visibly in size. In the case of Gonatopus erythrodes 

 (Perk.) parasitic on Deltocephalus inimicus nymphs, the last 

 stages are easily studied as the host is not very heavily chitinized 

 and opaque yellow in color. The dark jaws of the parasite can 

 be seen working in the interior of the host's abdomen first. 

 The entire abdomen is emptied of its contents before the parasite 

 directs its attention to the thorax. At this time, an hour after 

 the last molt, the hopper is still alive and responds to stimulus, 

 but it now dies very quickly as soon as the thoracic viscera are 

 attacked. The feeding seems to be a combination sucking, in 

 which the cone-like labium functions and the cutting by the 

 sharp mandibles. The head is attacked after the thorax, and 

 soon there is nothing left of the hopper but a mere shell. The 

 contents of the host seems to be partially liquified at the final 

 stages. About two hours elapse between the final molt and the 

 consumption of the host. 



