s mite is able to bury itself completely in the flesh, thereby
causing a red swelling with a pale pustulous centre containing watery
matter. If, in scratching, he is fortunate enough to remove the mite
before it enters, the part soon heals. But otherwise the irritation
lasts for two, three or four days, the pustulous centre reappearing as
often as it is broken.

"The animal itself, on account of its minute size, is seldom seen, and
the uninitiated, when first troubled with it, are often alarmed at the
symptoms and at a loss to account for them. Fortunately these little
plagues never attach themselves to persons in such immense numbers as do
sometimes young or so-called 'seed' ticks; but I have known cases where,
from the irritation and consequent scratching, the flesh had the
appearance of being covered with ulcers; and in some localities, where
these pests most abound, sulphur is often sprinkled during 'jigger'
season in the boots or shoes as a protection.

"Sulphur ointment is the best remedy against the effects of either of
these mites, though when that cannot be obtained, saleratus water and
salt water will partially allay the irritation.

"The normal food of either must, apparently, consist of the juices of
plants, and the love of blood proves ruinous to those individuals who
get a chance to indulge it. For unlike the true Jigger, the female of
which deposits eggs in the wound she makes, these Harvest-mites have no
object of the kind, and when not killed by the hands of those they
torment, they soon die victims to their sanguinary appetite."

[Illustration: 146. Astoma of the Fly.]

Another Leptus-like form is the parasite of the fly, described by Mr.
Riley under the name of Astoma? muscarum (Fig. 146). How nearly allied
it is to the European Astoma parasiticum we have not the means of
judging.

The European Tetranychus telarius Linn., or web-making mite, spins large
webs on the leaves of the linden tree. Then succeed in the natural order
the water mites (Hydrachna), which may be seen running over submerged
sticks and on plants, mostly in fresh water, and rarely on the borders
of the sea. The young after leaving the egg differ remarkably from the
adults, so as to have been referred to a distinct genus (Achlysia) by
the great French naturalist, Audouin. They live as parasites on various
water insects, such as Dytiscus, Nepa and Hydrometra, and when mature
live free in the water, though Von Baer observed an adu