April, 1918] Parasites of Leaf- Hoppers 201 



is split ventrally as was the first, and it is pushed outward by the 

 growth of the third instar within, breaking through the first 

 exuvium which is firmly attached to the host. This process 

 is repeated in the third molt, the second exuvium becoming 

 split open by the third. The exuviae become chitinized and 

 darken in color in some species. In Phorpas mirahilis (Perk.) 

 parasitic on Briicomorpha ocidatiis, this darkening and hardening 

 of the exuvium begins in the region of the spiracles, and at first 

 there is on each segment an oval black spot around each. 

 These later become confluent and it seems that apparently 

 after the skin is shed the air has something to do with the 

 hardening of the exuvium. The exuvium just shed also adheres 

 very closely to the growing larva which at first breathes through 

 the spiracles of this cast skin. Tracheae can be seen in direct 

 connection between the first pair of spiracles, even in the late 

 phasis of this instar. Just before the fourth molt, then, there 

 is present the fourth instar parasite larva, protected dorsally 

 by the third exuvium and laterally by the first and second. 

 During the late phases of the second instar, the parasite pushes 

 itself completely outside of the host, remaining attached by the 

 chitinous ring of the sac only, and with its head and posterior 

 extremity just within the body of the hopper. Later on the 

 head alone remains within the body of the host. 



With the final consumption of the host, the maggot with- 

 draws its head from within the shell of the latter, which it 

 quits, and goes off in search of a place to spin its cocoon. In 

 some species the dead shell of the host is jerked abruptly away 

 by the maggot (Misra, 1917). The larva is quite active, and 

 crawls around on its back similar to a Cotina grub by peculiar 

 peristaltic like movements, originating at the caudal end as a 

 constriction which progresses anteriorly. Sometimes as long as 

 a day is spent before the cocoon is started, and again it is begun 

 almost immediately, even beneath the dead host (Swezey, 1903). 

 The cocoons are spun either beneath the soil or above it on 

 leaves or other objects. Sometimes there is variation in 

 individuals in regard to the location of the cocoon. The first 

 generation cocoons of Gonatopus erythrodes (Perk.) were spun 

 below the soil, but some of these of the second were spun 

 above the soil on the sides of the cages. The cocoon is com- 

 pleted in from one to two days, although larvae that are to pass 

 the winter may be seen lining their cocoons for days after they 

 are apparently finished. 



