uropean T.
holosericeum Linn. is our species or not, we cannot tell. The larvae of
this and similar species are known to live parasitically upon Harvestmen
(Phalangium), often called Daddy-long-legs; and upon Aphides,
grasshoppers and other insects. Mr. Riley has made known to us through
the "American Naturalist" (and from his account our information is
taken), the habits of certain young of the garden mite (Trombidium)
which are excessively annoying in the Southwestern States. The first is
the Leptus? Americanus (Fig. 145), or American Harvest mite. It is only
known as yet in the larval or Leptus state, when it is of the form
indicated in the cut, and brick red in color. "This species is barely
visible with the naked eye, moves readily and is found more frequently
upon children than upon adults. It lives mostly on the scalp and under
the arm pits, but is frequently found on the other parts of the body. It
does not bury itself in the flesh, but simply insinuates the anterior
part of the body just under the skin, thereby causing intense
irritation, followed by a little red pimple. As with our common ticks,
the irritation lasts only while the animal is securing itself, and its
presence would afterwards scarcely be noticed but for the pimple which
results."

[Illustration: 145 _a._ American Harvest Mite; _b._ Irritating Harvest
Mite; the dots underneath indicating the natural size.]

The second species (Fig. 145 _b_, Leptus? irritans) is also only known
in the Leptus stage. It is evidently the larva of a distinct genus from
the other form, having enormous maxillae and a broad body; it is also
brick red. Mr. Riley says that "this is the most troublesome and,
perhaps, best known of the two, causing intense irritation and swelling
on all parts of the body, but more especially on the legs and around the
ankles. Woe betide the person who, after bathing in the Mississippi
anywhere in this latitude, is lured to some green dressing-spot of weeds
or grass! He may, for the time, consider himself fortunate in getting
rid of mud and dirt, but he will afterwards find to his sorrow that he
exchanged them for something far more tenacious in these microscopic
Harvest-mites. If he has obtained a good supply of them, he will in a
few hours begin to suffer from severe itching, and for the next two or
three days will be likely to scratch until his limbs are sore.

"With the strong mandibles and the elbowed maxillae which act like arms,
thi