28 HOW INSECTS ARE CLASSIFIED 
Psyllide, the psyllas. Minute, jumping forms. Plant feeders. 
Aphididex, the plant lice. 
Coecide, the scale insects and mealy bugs. 
The more important families of Heteroptera are as follows: 
Reduviide, the assassin bugs. Predaceous on other insects. Occa- 
sionally attack man. Have a strong, 
three-jointed beak. 
Tingitide, the lace bugs. Wings finely 
reticulate, looking like lace. Plant feed- 
ers. 
Acanthiide, including some plant feed- 
ers; also the common bedbug. 
Capside, the leaf bugs. Usually small. 
Often injurious. 
Lygeide, the chinch bugs. Destruc- 
tive plant feeders. 
Coreide, the squash bugs. Often ill 
smelling. Some species rather large. 
Pentatomide, the stinkbugs. The 
Fic. 26.—The giant water family includes both plant feeders and 
bug, wings folded. Sub-  predaceous forms. 
order Heteroptera. Origi- 
nal. 
Thyreocoride, the negro bugs. Very 
small forms. 
Pediculide, the sucking lice, parasitic on mammals. 
The number of described species in the Hemiptera exceeds 20,000. 
Coleoptera 
The order Coleoptera includes the beetles, readily distinguished, as 
a rule, by the fact that the front pair of wings are hardened and act 
simply as horny coverings for the larger, membranous hind wings, 
which are folded beneath the others when at rest. 
Metamorphosis is complete. There are four distinct stages, instead of 
three, as with all the other orders mentioned thus far. Eggs are laid 
by the adults, and from these hatch wormlike larvee, commonly called 
