LIBRARY

78 COLLEGE ENTOMOLOGY
seeds, and living plants to the extent of becoming injurious in greenhouses,
gardens, and fields. Forms living on the surface of water feed extensively
upon diatoms, desmids, algre. Snowfleas also eat pollen grains as do certain
of those that live on plants. Certain maritime species also feed upon carrion.
A very few are predacious and cannibalistic. Several species have become
beneficial because of their breeding in the filter beds of sewage disposal plants,
where they act as scavengers and keep the sand clean and sharp.
Myrmecophilous and tcrmitophilous species are blind and lack the springing
organ or furea.
For the most part the biology of these insects has received little attention,
and the habits and life histories of but a few species, including the lucerne flea,
Smynthurus viridis Linn., are recorded.
The known eggs are smooth or hairy and are laid singly or in groups of from
five to 100 in soil, humus, manure, under bark, leaves, stones; in rotten wood;
and similar places.
Nine genera and 12 species have been found in amber.
Collecting, Preservation, and MoulZting. -- Spring tails are readily collected
by hand by means of a small brush, or, much more effectively, with a bulb or
mouth pipette bottle. The use of a large Berlese funnel is of great value for
making careful collections and population st.udies. Leaves, soil, and refuse submerged
or washed in water in a container will also liberate the springtails, which
fioat on the surface.
They may be indefinitely preserved in 70 to 90 per cent alcohol, cleared in
KOH, lactic acid, or other clearing agent, and mounted into balsam or euparal.
Fresh specimens may also be mounted directly in Berlese or chloral hydrate
media and are greatly improved by heating at 120 0 F. for 1 hr. If dried and
ringed, such mounts will keep for many years.
External
Size - minute to very small.
Snape - slender to, almost globular.
Exoskeleton - soft, smooth or granular
cuticle often with scales, rods, or hairs.
Sometimes with circular pseudo celli on
the surface in the ONYCHIURINlE.
Color -- white, drab, or slate to bright
metallic hues.
Head - prognathous or hypognathous.
Eyes - compound eyes absent or represented
by a group of eight or fewer
ommata. True ocelli absent.
Antenn;e - tlsually four-segmented,
rarely five- or six-segmented. Sense
organs on segments III and IV.
ANATOMICAL CHARACTERS
Internal
Digestive System. Simple.
Alimentary canal - straight tube with
extensive mid-intestine divided into
four chambers in NEELIDlE.
Salivary glands - present.
Malpighian tubes - absent. Excretion
through the fat body and the epithelium
of the stomach. In the latter
case the waste materials are voided at
the time of molting.
CirCUlatory System.
Heart composed of a series of six chambers
with paired lateral ostia and anteriorly
prolonged into the aorta, which
may surround the fore intestine in
Anurida.