LIBRARY

HYMENOPTERA 621
differentiated mentum, submentum, cleft three-lobed ligula, and foursegmented
palpi, through various modified types to the sucking and
lapping bees which also retain the mandibles and have the glossa and
associated members variously developed and lengthened to form a
proboscis or tongue for collecting nectar of flowers. There is a marked
degree of change in all the different organs involved in feeding. They are
usually folded beneath the head at rest.
Mandibles - always present, well developed for cutting, biting, chewing,
scraping; broad, simple, or toothed.
Max£llm - variable and quite prominent. Palpi -one-, two-, [our-,
or six-segmented; short and vestigial in the long-tongued bees.
Cardines - well-developed chitinized rods connecting the labium
to the head. Stipites - narrow basal part of the maxilla which
may be fused with the palpiger. Lacinia - distinct or atrophied.
Galea - one- or two-segmented lobes. Cardo - stalked.
Labium - well developed and quite variable within the order; often
greatly attenuated. Mentum - of many shapes but often wide,
shield-like, and heavily sc1erotized. Submentum - small or well
developed. Larum - a thickened band connecting the cardines is
present. Ligula - a three-cleft lobe or a greatly lengthened part
of the sucking mouth parts.
Glossa - (thought to be the hypopharynx by some authors) short,
broad, simple or bifid, or very greatly elongated and grooved and
forms the most conspicuous part 6f the proboscis or tongue in bees;
may exceed the length of the body in Euglossa; extended by blood
pressure and held beneath body at rest. Labellum - the small
spoon-shaped or disk-like tip of the glossa in bees. Paraglossaabsent,
vestigial, small and lobed, or attenuated. Palpi - two- to
four-segmented, short or greatly lengthened and slender. Palpigermay
also be attenuated. The galea, labial palpi, and glossre are
all greatly lengthened into a tongue or proboscis in the longtongued
bees and the maxillre and labrum are hinged so as to permit
withdrawal and folding beneath the head.
Thorax - conspicuous and exceedingly variable in shape, usually remarkably
free, except that the basal abdominal segment is fused to the metathorax;
normally as wide as the abdomen; frequently humped dorsally owing to large
muscular lobes; separated into a. number of definite sclerites by well-defined
sutures.
Prothorax - generally small, sometimes almost vestigial; frequently
narrow and neck· like, and with the pronotum attachet;1 to the front of
the meso thorax.
M esothorax - usually very large and with prominent muscular lobes which
may form a conspicuous hump on the dorsum. the pleural plates fused
into the prepectus or ep{cttemium; the mesonotum is divided into the