lueless by the holes made by the larvae. When fully mature they drop to
the ground and complete their transformations.

The sheep bot-flies (Fig. 32) lay their eggs in the nostrils of sheep.
The larvae pass up into the frontal sinuses where they feed on the mucus,
causing great suffering and loss. Many other species of animals are
infested with their own particular species of bots. Several instances
are recorded where the oxwarble has occurred in man, always causing much
suffering and sometimes death.

One or more species of bot-flies occurring in the tropical parts of
America frequently attack man. The early larval stage soon after it has
entered the skin is known as the _Ver macaque_. Later stages as _torcel_
or _Berne_. The presence of the larvae produces very painful and
troublesome sores. It is supposed that the adult flies (one species of
which is _Dermatobia cyaniventris_) lay their eggs on the skin which
the larvae penetrate as soon as they hatch. It has also been suggested
that they might reach the subcutaneous tissue by migrating from the
alimentary canal as do some of the other bot-flies. A very serious eye
disease, _Egyptian opthalmia_, is known to be spread by the house-flies
and others. These flies are often abundant about the eyes, especially of
children suffering from this disease. It is suspected that certain small
flies (Oscinidae) in the southern part of the United States are
responsible for the spread of disease known as "sore eye."

FLEAS

The fleas used to be considered as degenerate Diptera and were placed
with that group but they are now classed as a separate order
(Siphonaptera). Within recent years these little pests have come into
special prominence on account of their importance in connection with the
spread of the plague. The fact that they are so abundant everywhere and
that they will so readily pass from one host to another makes the
possibility of their spreading infectious diseases very great. Besides
the kinds that are concerned in the transmission of plague, which are
discussed in another chapter, there are many other kinds infesting
various wild and domesticated animals and a few attacking birds.

One of the most important of these is the jigger-flea or chigoe
(_Dermatophilus penetrans_, Fig. 33). Various other names such as
chigger-flea, sand-flea, jigger, chigger are also applied to this insect
as well as to a minute red mite that burrows into the skin in much the
same way as