Some of the more important eastern species are as follows: (a) 
the human flea, Pulex irritans Lin., (b) the cat flea Ctenocepa- 
lides felis (Bouché), (c) the dog flea, C. canis (Curtis), and (d) 
the oriental rat flea, Xenopsylla cheopsis (Rothschild). The latter 
species is the principal vector of bubonic plague and may also 
transmit endemic typhus to man. 
Order THYSANURA 
Bristletails 
Bristletails occur abundantly in the forest in rotting wood and 
debris, under stones, and among fallen leaves, but none are in- 
jurious. They are distinguished by the style-like appendages on 
some of the abdominal segments, by the two or three tail-like ap- 
pendages at their posterior ends, and usually by their elongate 
bodies. 
Order COLLEMBOLA 
Springtails 
Springtails are very small, primitive, wingless insects. The 
body is covered by a soft exoskeleton and there is a single pair 
of antennae, each normally consisting of four segments. The 
mouth is located ventrally, and the mandibles and maxillae are 
either toothed for chewing, or styliform for sucking. There are 
three pairs of legs, each typically terminating in one or two claws. 
The first abdominal segment bears a ventral tube or collophore; 
there is a pair of small appendages fused basally on the venter 
of the third segment; and a furcula is appended to the ventral 
surface of the fourth. The latter operates as a spring and is 
capable of propelling the insect several inches into the air (512). 
Springtails are widely distributed and are among the most 
abundant of insects. They are found in all sorts of places, many 
unexpected such as on the surface of snow and on the surface of © 
water. In the forest they are found in moist soil, among dead 
leaves, in dead and decaying logs, under loose bark, and in bark 
crevices of living trees. The majority feed on algae, fungi, and 
lichens and other living or dead plant matter. Pollen from conifers 
is favored by some species in the spring. Some may be attracted 
in large numbers to decaying fruit and animal matter. Others 
may be attracted to sap flowing from trees in the spring. 
Springtails tend to be beneficial in the forest because of their 
help in the reduction of litter and in the formation of humus. 
Bellinger (54) published a key to species occurring in eastern 
America. 
Order THYSANOPTERA 
Thrips 
Thrips are small slender-bodied insects, usually from 0.05 to 
5.0 mm long. Adults are either wingless or have four long, narrow 
fringed wings with few or no veins. The mouth parts are of the 
sucking type; the antennae are usually short and 6- to 10-seg- 
Al 
