1 94 Bugs, Cicadas, Aphids, and Scale-insects 



Bemis (Proc. U. S. Nat. Mus., vol. 27, 1904), who has studied the Pacific 

 Coast forms. Mrs. Bemis found twenty hitherto unknown species of mealy- 

 winged flies in easy collecting 

 range of Stanford University, 

 and these twenty kinds added 

 to those already known make a 

 total of sixty different species so 

 far recorded from the United 

 States. There are certainly 

 many more species yet unde- 

 scribed. 



The mealy-winged flies have 

 some, though not a large, eco- 

 nomic importance. One or two 

 species, Aleyrodes vaporariorum, 

 FIG. 267. Pupa of Aleyrodes merlini, showing etc., are recognized as pests in 

 long waxen tufts. (After Bemis; much en- greenhouses; one, A. citri. is a 

 larged.) . . 



pest of oranges, and another, 



A. packardi, injures strawberry-plants. In all these cases probably as much 

 injury is done by the suffocating fungus growth that is supported by the 

 secreted honey-dew as by the direct sap-sucking of the Aleyrodes themselves. 

 Fumigation by hydrocyanic gas (see p. 189) is probably the best remedy 

 for the greenhouse and orange mealy-wings, and spraying with kerosene 

 emulsion (see p. 189) the best for the strawberry Aleyrodes. 



SUBORDER HETEROPTERA. 



KEY TO FAMILIES OF THE HETEROPTERA (INCLUDES BOTH NYMPHS AND ADULTS). 

 (ADAPTED FROM WOODWORTH, WITH SOME ADDITIONS.) 



Antennae shorter than the head: aquatic or shore insects. 



With two ocelli (Toad-bugs.) GALGULID^:. 



With no ocelli. 



Hind feet without claws; aquatic insects. 



Prothorax overlapping the head above (Back-swimmers.) NOTONECTID.E. 



Head overlapping prothorax above (Water-boatmen.) CORISID.E. 



Hind feet with claws. 



With two long processes on tip of abdomen which can be held together to form 



a tube (Water-scorpions.) NEPIDJE. 



Without abdominal processes, or if any, short flattish retractile ones. 



Hind legs broad and flat (Giant water-bugs.) BELOSTOMATID.E. 



Hind legs slender NAUCORID^E. 



Antennae at least as long as the heaJ: a few aquatic forms, but mostly terrestrial. 

 Head as long as the whole thorax (Marsh-treaders.) LIMNOBATID.E. 



