Handbook of Medical EntomologyRiley, William A. (William Albert)
Science
Handbook of Medical Entomology
Riley, William A. (William Albert)
Insect pests; Insects as carriers of disease; Medical parasitology
The eggs are white, changing to yellow and pink before hatching. The
young hatch within twenty days and there are four nymphal stages. In all
these stages the insect is active and predaceous, the mouth-parts (fig.
72) being powerfully developed. The eggs are normally deposited, and the
early stages are undoubtedly passed, out of doors, the food of the
immature forms being other insects. Immature specimens are rarely found
indoors. It winters both in the partly grown and adult stage, often
under the bark of trees or in any similar protection, and only in its
nocturnal spring and early summer flights does it attack men. Marlatt
states that this insect seems to be decidedly on the increase in the
region which it particularly infests,--the plains region from Texas
northward and westward. In California a closely related species of
similar habits is known locally as the "monitor bug."
The effect of the bite of the giant bed-bug on man is often very severe,
a poisonous saliva apparently being injected into the wound. We have
discussed this phase of the subject more fully under the head of
poisonous insects.
_Conorhinus megistus_ is a Brazilian species very commonly attacking
man, and of special interest since Chagas has shown that it is the
carrier of a trypanosomiasis of man. Its habits and life history have
been studied in detail by Neiva, (1910).
This species is now pre-eminently a household insect, depositing its
eggs in cracks and crevices in houses, though this is a relatively
recent adaptation. The nymphs emerge in from twenty to forty days,
depending upon the temperature. There are five nymphal stages, and as in
the case of true bed-bugs, the duration of these is very greatly
influenced by the availability of food and by temperature. Neiva reckons
the entire life cycle, from egg to egg, as requiring a minimum of three
hundred and twenty-four days.
The nymphs begin to suck blood in three to five days after hatching.
They usually feed at night and in the dark, attacking especially the
face of sleeping individuals. The bite occasions but little pain. The
immature insects live in cracks and crevices in houses and invade the
beds which are in contact with walls, but the adults are active flyers
and attack people sleeping in hammocks. The males as well as the females
are blood suckers.
Like many blood-sucking forms, _Conorhinus megistus_ can endure for long
periods without food. Neiva received a female specimen which had been
for fifty-seven days alive in a tightly closed box. They rarely feed on
two consecutive days, even on small quantities of blood, and were never
seen to feed on three consecutive days.
Methods of control consist in screening against the adult bugs, and the
elimination of crevices and such hiding places of the nymphs. Where the
infestation is considerable, fumigation with sulphur is advisable.
PARASITIC DIPTERA OR FLIES
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