June, 191S] Parasites of LeaJ-IIoppers 289 



this paper no sueh tissues were found. Since many Cicadellid 

 species are attacked and parasitized by dryinids after they have 

 become sexually mature it is doubtful in these cases whether the 

 gonads would be completely disintegrated. In fact in para- 

 sitized DeltocepJialiis sayi they are present, but modified in 

 that the germ cells are not matured after a certain point is 

 reached in the parasites growth, so that if reproduction is 

 not entirely stopped it is greatly impaired. 



In Erythronenra comes the hypertrophied tissue is probably 

 caused by a stimulation set up by the presence of the parasite 

 in the host's tissues or to some toxic substance secreted by it. 

 That the sting alone will not produce such a result is proved 

 by the fact that hoppers that have been stung but not oviposited 

 in develop and mature in a perfectly normal manner. 



A comparison of the genitalia of both sexes in Erythroneiira 

 comes in normal and parasitized individuals showed no 

 differences. 



CONCLUSIONS. 



1. The larva of Aphelopiis species secretes some toxic 

 substance into the tissues of the host or otherwise stimulates 

 the abnormal development of the hypodermal tissues into a 

 hypertrophied cell mass. 



2. This is developed at the expense of the gonads which 

 do not develop upon the maturity of the host. 



3. This is surrounded by a membrane and functions as a 

 means of absorbing food from the body of the host for the 

 parasite and is itself not consumed until just before the death of 

 the host. 



4. The genitalia of the host are not modified by the parasite. 



5. A wall of cells is developed around the wound produced 

 in the body wall of the host. 



G. The malpighian tubules of the host are underdeveloped. 



7. Gonatopiis, Ilaplogouatopus, and Chelogynus species 

 that parasitize nymphs stop further development of the host 

 which does not become mature. 



8. Adults parasitized by these genera, that have become 

 sexually mature, may still reproduce at first but there are 

 evidences that soon reproduction is greatly impaired or entirely 

 stopped. 



9. The hypertrophied tissue has not been found produced 

 by any genus other than Aphelopiis. 



