mented; the tarsi are 1- to 2-segmented, with one or two claws, 
and are bladderlike at the tip. 
Thrips are frequently extremely abundant on flowers. Others 
occur on foliage, fruit, bark, and fungi and in debris. A number of 
species cause considerable damage to cultivated plants, but only 
a few have been reported injurious to trees (17). 
Liothrips umbripennis Hood became abundant enough on chest- 
nut oak in New Jersey in 1937 to cause the curling of leaves. 
Gnophothrips fuscus (Morgan) has damaged pine seedlings in 
nurseries in New York and Rhode Island. Jack pine growing in 
mixed stands on rocky slopes in Ontario has also been slightly 
damaged. Female strobili of slash pine growing in Florida have 
been severely damaged (216). Damage to the strobili consisted of 
punctures and abrasions on the scales and bracts of flowers and 
conelets. Heavy infestations resulted in shriveled conelets and 
the death of affected flowers. The flewer thrips, Frankliniella 
tritici (Fitch), feeds on the flowers and flower buds of hawthorn. 
This sometimes prevents the buds from opening. 
Order PSOCOPTERA 
Book lice and psocids 
Book lice and psocids are small, soft-bodied, winged or wing- 
less insects, usually less than 6 mm. long. The more typical pso- 
cids have well-developed wings and bear a striking resemblance 
to aphids of the order Homoptera. The wings are held rooflike and 
almost vertically over the body while at rest. Book lice are either 
EIS or possess only vestigial wings, and are about 1 mm. 
ong. 
Psocids are found under stones, on or under the bark, and on 
the foliage of trees or shrubs. They are not injurious to trees, 
but they may be a nuisance, especially when they occur in large 
numbers around residences or in recreational areas. They feed 
on fungi, lichens, and probably other vegetable matter. 
Book lice occur most commonly in damp, dark rooms, not gen- 
erally used. They are occasionally found in old books where they 
feed on the paste of the bindings. Sometimes they are abundant 
enough to cause serious damage. 
Order NEUROPTERA 
This order contains a wide variety of terrestrial and aquatic 
insects. The adults have two pairs of large, membranous, leaf- 
like wings which they hold roof-like over the abdomen while at 
rest. The antennae are generally long and many-segmented; the 
tarsi are five-segmented and there are no cerci. The larvae are 
practically all carbiform and are usually armed with very large, 
curved mandibles. 
FAMILY CORYDALIDAE 
DOBSONFLIES 
The best-known species of this family is the dobsonfly, Cory- 
dalus cornutus (L.). The adult, especially the male, occasionally 
reaches a length of 100 mm., has two long curving pincers or 
42 
