J 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 
!ar|ed W ) aXen (After Bemis; mUCh en ‘ greenhouses; one, A. citri, is a 
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,e. 
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 Whe.(Water-scorpions.) Nepid^e. 
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 head: a few aquatic forms, but mostly terrestrial. 
Head as long as the whole thorax.(Marsh-treaders.) Limnobatid^e. 
