THE EED SPIDER ON" COTTON. 



53 



S phaerophoria cylindrica Say. — ^Although a trifle smaller, this syr- 

 phid (fig. 15) resembles the preceding species superficially. The sm.all, 

 parchment-like puparia are frequently observed on leaves support- 

 ing active or exterminated aphid and mite colonies. They become 

 very common toward the end of August on tomato vines infested by 

 mites, upon which they exert marked control. 



Toxomerus duplicatus Wied. — This very small, yellowish species 

 was occasionally taken on infested cotton leaves toward late summer. 

 Its small size would indicate, possibly, that it is better qualified as 

 an enemy of the red spider than the larger species. Its occurrence, 

 however, is rather limited. 



'Fig. 15. — Sphaerophoria cylindrica, an enemy of the red spider: a. Female fly; 6, dorsal view of abdomen 

 of male; c, hypopygium of male, lateral view. Much enlarged. (Webster and Phillips.) 



Like most of the other red-spider predators, the syrphids in turn 

 have their enemies. In fact, they are usually well supplied with 

 parasites, 7 species having been reared during the last few seasons. 

 "We are not in a position to furnish specific data connecting these 

 parasiUis with their r(ispective hosts, but will merely list them col- 

 lectively as enemies of the four syrphid species. They are: Cliry- 

 sopopJuigus compressicomis Ashm., Pachy neuron allograptae Ashm., 

 Pachyneuron sp., Syrphopliar/us raesof/raptae Ashm., Tetrasticlius sp., 

 JJlplazon laetatorius Fab,, and a species belonging to the tribe Mirini. 



