LIBRARY

374
COLLEGE ENTOMOLOGY
IMPORTANT ANATOMICAL CHARACTERS - LARV A3:
External
Si2:e - minute, to medium.
Shape - thysanuriform, robust, or disk·
like.
Exoskeleton - thin, elastic; with hairs,
spines, scales, macrotrichia, microtrichia,
dolichasters. *
Color - cryptic and dull or green, pinkish,
yellow, mottled.
Head - well developed, free, prognathous,
small in some families, heavily chitinized,
strong.
Eyes - simple, in a group of five, six, or
seven on each side; none in !thone.
Antenn;:e - simple, setiform, few- to
many-segmented.
Labrum - generally reduced, often only
a slender margin of the clypeus.
Clypeus - broad triangular plate.
Mandibles - variable, sharp, short or
long, straight or curved, simple or
toothed; grooved on ventral side and
combined with maxil1re to form two
sucking tubes.
Maxillill - reduced to separate blades
usually similar in size and form to the
mandibles, under which they fit to
close the mandibular grooves.
Labrum - reduced, may be longitudinally
divided.
PalPi - usually shorter than antenrue,
three- to seven-segmented.
Neck - connects head and prothorax and
is considered as part of latter; short and
membranous or long and tube-like, often
conspicuous.
Thorax - Prothorax divided into three
parts.
Meso- and metat/lOrax similar, normal.
Legs - uniform; COXill -large and
widely separated; trochanter, - small;
femora - equal to or smaller than
tibire: tibire -longest segments; tarsi
- one-segmented (tibia and tarsus
fused in all legs of !thane and the hind
legs of the myrmeleonids and ascalaphids);
claws - usually two (one in
SISYRIDA3:) ; empodium - present in
Internal
Digestive System.
Mouth - no true mouth exists; the
liquid food enters through two chan·
nels formed by the mandibles and
maxi1lre. Food sucked into pharynx
by pharyngeal pump.
(Esophagus - either constricts or has a
valve.
Crop - thin-walled, large, occupies
much of the thorax.
Mid-intestine - a large, blind sac occupying
anterior half of the abdomen.
Malpighian tubes - eight (six in CONI­
OPTERYGIDfE) arising from ex·
tremity of mid-intestine and extend·
ing: forwards and backwards. May
secrete silk towards end of larval
period.
Hind intestine closed to passage of food;
a fold envelops apices of Malpighian
tubes and enables contents of latter to
enter silk reservoir.
Silk reservoir - thin-walled sac which
supplies fluid for spinning silk for
cocoon and other purposes.
Rectum - narrow, leads to anus; anal
papilla extrudes as spinneret for spin·
ning the cocoons.
Salivary glands - empty into the tubes
at the bases of the jaws and extend
along sides of cesophagus.
Circulatory System.
Normal. The dorsal vessel narrows in
the pro thorax to form an aorta.
Respiratory System.
Spiracles - one pair prothoracic. Eight
pairs abdominal on first eight seg·
ments. Two main longitudinal tracheal
trunks. Tracheal gills in SISY­
RIDfE.
Nervous System.
Supra- and sub-resophageal ganglia
within the head.
Three thoracic and eight abdominal
ganglia connected by a pair of com·
missures.
. * Dolichasters are funnel-shaped organs arising from the centers of chitinous papillre of the
mtegument. A transverse section reveals a star-shaped structure_ They occur in Psychoj16is
and the myrmeleontid groups.