
773 

INSECTS AND DISEASE 
THE SUCTORIA OR FLEAS 
The Suctoria or fleas are small, wingless, jumping insects which 
are strongly compressed sideways. They are all parasitic, when 
adult, on warm-blooded animals; but the footless, worm-like larve 
are not. Adults of both sexes have piercing mouth-parts and suck 
blood. The larve, however, have chewing mouth-parts and feed 
on more solid organic material. The larve live in dust and refuse 
on the floor or ground and pupate there, usually in thin silken 
cocoons. 
The Dermatophilidz, one of the principal families of Suctoria, 
have the segments of the thorax much shortened and constricted, 
but the side-plates of the metathorax extend over two or three 
abdominal segments; the third antennal joint has no completely 
separated false joints; and the fully developed female, living beneath 
the skin of her host during her final development, has a greatly 
dilated abdomen. The most familiar example is Dermatophilus 
penetrans, the “‘chigoe,” “‘chique,’’ “chigger,”’ “‘jigger,’’ or “‘sand- 
flea.’ The fertilized female burrows under the skin, especially 
about the toes, and causes a nasty ulcer. The eggs which she lays in 
the ulcer, or the larve which hatch from them, drop to the ground 
for further developmert. The female may be picked or squeezed 
out of the ulcer and the wound should then be carefully treated to 
clear away the pus. Asa method of control—even if not for other 
reasons!—the habitations of men and domesticated animals should 
be cleaned to destroy the larva. This species is found in the warmer 
parts of America and in Africa. Members of the family Pulicide, 
on the other hand, do not have the thoracic segments much con- 
stricted and shortened but the side plates of the metathorax extend 
over only one abdominal segment; the third antennal joint has nine 
more or less distinctly separated false joints; the spines on the hind 
tibiz are in pairs, are few in number, and are not in a very close-set 
row; and none of the species burrow under the host’s skin. In the 
senus Ctenocephalus both the head and the pronotum (front section 
of the thorax) have stout, spine-like bristles (ctenidia); the last tarsal 
joint has four pairs of lateral spines and, in distinction from /Veopsy/la, 
the eyes are distinct. In Ceratophyllus the head has no ctenidia but 
the pronotum does; the last tarsal joint has five pairs of lateral spines. 
In Pulex and Xenopsylla neither the head nor the pronotum has 
ctenidia. The distinction between these two genera is chiefly based 
49 
