the female of the flea. So although they are entirely
different creatures you can never tell from the common name, whether it
is the flea or the mite that is being referred to. Both the male and
female jigger-fleas feed on the host and hop on or off as do other
fleas, but when the female is ready to lay eggs (Fig. 34), she burrows
into the skin. Her presence there causes a swelling and usually an ulcer
which often becomes very serious, especially if the insect should be
crushed and the contents of the body escape into the surrounding tissue.

These little pests are found throughout tropical and subtropical America
and have been introduced into Africa and from there have spread to India
and elsewhere. They attack almost all kinds of animals as well as many
birds, being of course a source of great annoyance and no inconsiderable
loss. They are more apt to attack the feet of men, especially those who
go barefooted. Sometimes they occur in such numbers as to make great
masses of sores.

On account of being such general feeders they are difficult to control,
but some relief may be obtained by keeping the houses and barns as free
as possible from dirt and rubbish and by sprinkling the breeding-places
of the pest with pyrethrum powder or carbolic water. Those that gain an
entrance into the skin should be cut out, care being taken to remove the
insect entire.

BEDBUGS

In the order Hemiptera, or the true "bugs" in an entomological sense, we
find a few forms that may carry disease. The bedbug (Fig. 35) (_Cimex
lectularis_) has been accused of transmitting plague, relapsing fever
and other diseases. Very recent investigations show that the common
bedbug of India (_Cimex rotundatus_) harbors the parasite that causes
the disease known as _kala azar_, and there is no doubt that it
transmits the disease.

LICE

The sucking lice (Fig. 36) which also belong to this order are suspected
of carrying some of these same diseases. It is thought that the common
louse on rats (_Haematopinus spinulosus_) is responsible for the spread
from rat to rat of a certain parasite. (_Trypanosoma lewisi_), which,
however, does not produce any disease in the rats, but if they are
capable of acting as alternative hosts for such parasites, it is quite
possible that they may also carry disease-producing forms.

[Illustration: FIG. 33--Chigo or jigger-flea, male (_Dermatophilus
penetrans_). (After Karsten.)]

[Illustration: FIG. 34--Chigo, femal