24 



follow. As the eggs of the differential are not deposited before 

 August 15, the appearance of the parasites long after the young- 

 grasshoppers emerge suggests that, were they to appear earlier, the 

 species would perish for lack of food. Those reaching the adult as 

 earl j as June find food in the eggs of species of grasshoppers which 

 deposit their eggs in the spring as Schistocerca americana, or in those 

 of double brooded species, as Chortophaga viridifasciata. 



Parasites of nymphs and adults. — As the fight against the grasshop- 

 pers progressed it was thought of interest to determine, as far as 

 possible, all of the natural agencies at work, that with a fuller knowl- 

 edge of these we might better know how to direct the expensive and 

 time-consuming artificial measures, or knowing more accurately 

 nature's rigid methods of establishing equilibration among the beings 



Fig. 9.—Sarcophaga mrraceniss: • Larva at right; adult in center; puparium at left— enlarged (from 



Howard). 



in her charge we might assist and encourage her with less expense 

 and more profit than carry out our own. 



From time to time hundreds of grasshoppers were collected and con- 

 fined to cages where each day quantities of fresh food were given them. 

 As the later stages of the grasshoppers were reached maggots were 

 noticed emerging from the conjunctivae (sutures) of the abdomino- tho- 

 rax and head. None, however, appeared until after the specimens had 

 died, either from the conditions of confinement or from the attack of 

 the parasites. As the collections were made after the " South African 

 fungus" had been spread, many of the specimens were attacked by 

 the parasitic flies and the fungus as well. Just to what extent the 

 attack of the fungus encouraged the attack of the flies we were unable 

 to determine. 



