145] 



LIFE HISTORY OF GOKDIUS AND PARAGORDIUS—MAY 



25 



TABLE I 



RESULTS OF INFECTING Orchelimum vulgar e with larvae 

 OF Gordius robustus in the laboratory 



Infection takes place at or near the place where the larvae have hatched. 

 In the spring of 1914 Gordius was very abundant in all of the streams at 

 which collections were made. Later all specimens of Orchelimum vulgar e 

 collected near these streams were equally and heavily infected. During 

 the summer of 1915 the streams were continually flooded and, judging 

 from the scarcity of Gordius in the fall of that year and the following spring 

 the infection must have been very light. The only place where any appre- 

 ciable infection can have taken place is a stream north of the city which 

 ordinarily goes dry during the summer months. It was in that locality 

 that adult worms were found in the spring of 1916 and the Locustidae were 

 found to be heavily infected later in the summer. The stream west of 

 Champaign which had supplied the major part of the material in 1914 is 

 bounded by narrow, steep banks and the high water must have prevented 

 the grass from growing in the bed of the stream as usual. This stream is 

 also becoming more and more polluted with sewage and other refuse. Of 

 453 specimens of Orchelimum vulgare collected along the bed of this stream 

 August 28 to September 4, 1916, only six specimens or 1.5 per cent were 

 found to be infected. I had not succeeded in finding any specimens of 

 Gordius in the stream the previous spring. Of 555 specimens of Locustidae 

 collected in the bed of the stream north of Urbana along the distance show- 

 ing the heaviest infection 110 specimens or about 20 per cent were infected 

 and yielded 164 parasites while in the other collection no host had more 

 than one parasite. A collection of 143 hosts along the same stream, but 

 starting where the previous collection had left off, contained 8 infected 

 specimens or 6 per cent and only a single parasite was found in each host. 



