a handbook of the mosquitoes of north america - Systematic Catalog ...

CHARACTERISTICS 19
is broad, somewhat flattened and rounded in front. Behind,
it is sharply constricted and is inserted on the thorax by a
very narrow neck, the opening into the head being surrounded
by a chitinous collar. The antennae are inserted on the outer
anterior angles of the head. Behind the antennae, near the
posterior border of the head, are situated the two pairs of eyes ;
the large compound eyes are in front and a small pair of ac-
cessory eyes immediately behind them. Between the anten-
nae the anterior margin colnsists of the narrow clypeus. Aris-
ing from the clypeus is the labrum. Its median free lobe is
marked by two prominent spines which arise from the anterior
margin of the clypeus, one on each side (Cl. Fig. 9A) The
other mouthparts lie on the ventral side of the head.
The antenna is cylindrical, slightly curved inwards and con-
sists of a single segment. It tapers but slightly to the tip. The
apex is truncate and bears a conical sensory organ, a single
stout spine, two slender spines and a short stout conical spine.
About the middle, on the upper surface arises a fan-shaped
group of fine hairs from a single stout base, the a,demzal tuft.
The antenna1 shaft is beset with small forward directed spines.
At the base of the antenna and arising from the front is a
prominent hair tuft-the anteantcnmd hair tuft. Between the
antenna1 tufts and arising on each side of the middle line of
the head are two pairs of hair-tufts. The anterior pair, each
of which consists of a single hair in this species, is called the
lozver head tzt ft or hair:
hea,d tuft, or hair.
the posterior is kno’wn as the zapper
These tufts are rather constant in number
of hairs and polsition for each species and are used extensively
for diagnostic purposes. Other small hairs may be found on
the head but they do not seem to have any significance for the
separation of species.
The mouthparts consist of the labrum, mandibles, maxillae
with their palgi and the labium. The labrum is a complicated
organ and is highly developed for the purpose of sweeping
food into the. mouth opening. It consists of three portions, a
median free lob’e, the so-called palatwn, which projects from