165J LIFE HISTORY OF GORDIUS AND PARAGORDIUS—MA Y 45 



remain in a large mass enveloping the lobes of the female, but pass into the 

 seminal receptacle in less than a day. 



On July 9 a mutilated male was obtained from the lake. It consisted of 

 the posterior end of the body with more than a third of the body removed 

 from the other end. A female was placed with this male and after a few 

 hours showed a mass of spermatozoa at the posterior end. 



The eggs are deposited in long strings about 0.2 mm. in diameter, and 

 adhere very tenaciously to each other. Females will deposite eggs in 

 aquaria just as freely as in nature. When grass or other objects are present 

 the strings are wound around them, otherwise they are deposited in large, 

 tangled masses. 



Males and females that have discharged their reproductive products 

 die and disintegrate in the manner described for the previous species. 



EARLY DEVELOPMENT 



The observations made on the development and structure of the larva 

 are, for reasons stated before, only fragmentary and can not be included 

 in this report. 



PARASITISM 



Like Gordius robustus, this species enters a host as larva and undergoes 

 its entire development in the parasitic stage. 



Hosts. Both at Douglas Lake and Urbana parasitic stages were found in 

 adults or older nymphs of Gryllus assimilis (Fabricius) as defined by Rahn 

 and Hebard (1915). At Douglas Lake they were also found in Nemobius 

 fasciqtus (DeGeer). The specimen staken from Nemobius were as a rule 

 smaller and shorter in proportion to their diameters than were those taken 

 from Gryllus. 



Altho the larvae penetrate the tissues of various species of aquatic 

 animals it has been impossible to determine if any or all of these animals 

 may serve as intermediate hosts. If some of them do serve as intermediate 

 hosts they must serve merely as carriers. The delicate tissues that appear 

 as soon as the larva begins to change into the parasitic form make it impos- 

 sible for a further change of hosts to take place without causing the destruc- 

 tion of the parasite. Attempts to infect the hosts artificially proved 

 unsuccessful. 



Infection. Only two infected hosts were taken at Urbana. At Douglas 

 Lake in 1915 adults were emerging from the hosts in large numbers the latter 

 part of June and young parasitic stages were still found by the middle of 

 August. Early parasitic stages were obtained thruout the entire summer. 



Infection in this species also was extremely local and slightly heavier in 

 females than in males. Of 125 males of Gordius assimilis collected on the 

 hill just above the laboratory and within half a mile of the lake 6, or 5 per- 

 cent, were infected, yielding 7 parasites. Of 152 females collected at the 

 same place 24 were infected, making an infection of about 17 per cent and 



