1918] Glaser and Wilcox — A Mermis Epidemic amongst Grasshofpers 13 



he says was common in Locusta Carolina near Philadelphia; but 

 there can be no certainty about the matter until males of the pres- 

 ent species are obtained and a comparison made with Leidy's 

 material, which may or may not be in existence." Dr. Cobb 

 further stated that after the nematodes leave the grasshoppers, 

 they make their way into the soil and that their further history is 

 obscure. 



In Vermont the nematodes parasitized both M. atlanis and M. 

 bivittatus. The worms seem to leave the bodies of the grasshoppers 

 when these insects are maturing. We had not the opportunity 

 to observe grasshoppers in the early stages of parasitism, but in 

 August and September dissection of a large number of the insects 

 showed that the worms were located wdthin the body cavity. 

 Later in the season, when the worms are about to emerge, the 

 grasshoppers fall over on one side, kick for a time and then die. 

 In the meantime, the worms gradually bore their way through 

 the body wall and reach the exterior after which they make their 

 way slowly into the earth. Usually only one worm parasitizes a 

 grasshopper, but by dissection we have often found two or three 

 and in one case we found forty. Needless to say, that when an 

 insect contains so many worms the abdomen is considerably 

 swollen. 



The length of these female worms varied from two to eight 

 inches. It is extraordinary that with hundreds of hoppers dying 

 everywhere, we were unable to find any males. 



A great many nematodes, at one stage of their Ufe cycle, seek 

 water on leaving their hosts and there mature, or wait until another 

 host presents himself. We placed about two dozen of our worms 

 in a bowl of water in which they seemed to flourish for about two 

 weeks. However, the localities where the hoppers, and conse- 

 quently the worms abounded were free from streams, ponds or 

 marshes of any kind. The Connecticut River flows through a val- 

 ley at a distance of about one-half mile so it seemed vmlikely that 

 the worms would travel so far. In all probability, we thought, the 

 worms make their way into the soil on leaving the insects and this 

 we found true. We placed recently dead parasitized hoppers in 

 boxes containing earth. In about three daj's the boxes were ex- 

 amined and the worms were found coiled up at a depth of about 

 ■one foot. Often a number would be coiled up together in one 



