LIBRARY

HYMENOPTERA 625
II to IX and X or absent on VII and VIII, or X. Abdomen may have
ventral eversible glands. The wood-boring forms are apodous; cerci
present or absent; free living on the host plants or in fruits, leaf rolls,
mines, stems, or galls.
In the CLISTOGASTRA or higher forms the larvre are highly specialized
for a particular environment, and some are subject to strict
and precise care. These specializations consist chiefly in reduction of
parts and the larvre appear to be an undifferentiated mass enclosed in a
thin skin; being apodous, often headless, and usually without appendages
or external organs of any kind.
Pupre - free; often enclosed in a thin parchment-like cocoon or in closed
cells of variable structure above or below ground.
IMPORTANT INTERNAL ANATOMICAL FEATURES OF THE ADULTS
Alimentary Canal.
Mouth cavity - variable and often large; leads into the pharynx.
Injrabuccal cavity or chamber - in ants a bag-like sac below the floor of the
mouth which retains and rejects solid matter after the juices are strained
into the mouth (Imms).
Salivary glands - well developed; one pair in head and one pair in the thorax
of bees - four ducts open on the hypopharynx; a mandibular gland also
may be present in certain bees and wasps.
(Esophagus - narrow and tUbe-like; long or short; dilated into a honey
stomach in bees.
Crop - greatly extended to serve as a honey reservoir and fills and expands
the gaster in honey ants.
Proventriculus - a narrow passage between the crop and the stomach charact.eristic
of the order; with valves and pump action in the honeybee to
force the nectar into the stomach. .
Stomach or ventdculus - atrophied or small in certain forms, or very large
and U-shaped in Vespa and Apis.
Peritrophic membrane - usually wanting, perhaps because of extensive liquid
foods.
Ileum - small intestine - short and simple or long and looped.
Malpighian tubes - exceedingly variable in number: 6-20 in ants, 20-25 in
sawflies, 20-30 in leaf-cutting bees, 50-60 in most ichneumon flies; 100
or more in bees; and 100-125 in many wasps; separate or in two to four
groups or bundles; open separately into the ileum.
Rectum - large chamber with rectal papillre: three in ants, four in certain
ichneumons, and six in the honeybees and in most other members of the
order. .
Circulatory System. Heart and aorta may be well developed and with four
or five chambers in abdominal segments III to VI in the honeybees and IV
to VIII in the ants. .