THE RED SPIDER ON COTTON. 53 
Sphaerophoria cylindrica Say.—Although a trifle smaller, this syr- 
phid (fig. 15) resembles the preceding species superficially. The small, 
parchment-like puparia are frequently observed on leaves support- 
_ing active or exterminated aphid and mite colonies. They become 
_yery 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 
parasites with their respective hosts, but will merely list them col- 
lectively as enemies of the four syrphid species. They are: Chry- 
sopophagus compressicornis Ashm., Pachyneuron allograptae Ashm., 
-Pachyneuron sp., Syrphophagus mesograptae Ashm., Tetrastichus sp., 
Diplazon laetatorius Fab., and a species belonging to the tribe Mirini. 
