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COLEOPTERA 547
and often curled up and forwards over the rest of the body; integument soft,
leathery, or hard; smooth and shining or partly to wholly pilose or densely
hairy. Head large, often as wide as the rest of the body, free, prognathous.
Eyes small or large, rarely wanting. Ocelli, consisting of one or two, may also
be present. Antennre 10· or 11- (rarely nine.) segmented, variously placed on
the margins of the head, filiform or clavate. Mouth parts conspicuous and with
very large powerful mandibles which may overlap when closed. Legs short
and strong and permitting rapid movements.
Tarsi variable, usually 5-5-5, but may be either
4-5-5 or 3-5-5. Elytra short, never as long as
the abdomen, usually less than half as long;
absent in littoral and other forms. Wings absent,
reduced, or developed for flight. Abdomen
truncate or pointed, flexible, moved up and
down over back, and aids in folding the wings
and perhaps also for protection; six or seven
visible sternitcs; spiracles visible or hidden; and
with styliform appendages. The Iarvre do not
differ greatly in appearance from the adults
except in the lack of elytra and wings. They are
often similarly colored and move about like the
mature forms.
These beetles form one of the largest groups
of insects and include more than 20,000 species.
They occur throughout the world and represent
a wide variety of forms and habits. As a whole
they are carnivorous and saprophagous and,
like all predators and many phytophagous in­
sects, they are also cannibalistic_ The adults
occur in and about carrion and decaying organic
matter, dung, and debris wherever they
are able to find food. They form the largest
FIG. 184. The hairy rove beetle,
Creoplzilu.s maxillosus flillosus (Gra.venhorst).
(From Insects of Western
Nort/! America.)
group of myrmecophilous insects with more than 300 species associated with
ants.
A number of very small species like Anthobium minutum Fab. and A. torquatum
Marsham of Europe, Trogophlreus pusillus (Gravenhorst) of Europe and
North America, and Apocellus sphrericollis Say of North America feed on the
foliage of succulent plants, on pollen, and on strawberries. Many species are
odorous and eject volatile liquids as a meanll of protection. T4ese fluids can
actually be seen escaping from the tip of the abdomen as a very fine mist expelled
with much force. Others exude drops which are smeared upon the adversary
by means of the flexible abdomen. In size the members vary froin the
minute Oligota pusillima Grav., 0.7 mm. long, of Europe and Noi:th America to
the largest European species, StaphyUnus tenelJricosus ,Grav., which measures
22-30 mm. in length, and S. alens Milller, which is, 20-32 rom. long.