Continued
They are so small that
even the adults are barely visible to the unaided eye. Adult
females are 0.33 to 0.45 mm long, and the males, 0.20 to 0.24
mm. The mites are a translucent, dirty-white color, with the
more highly chitinized (shell or nail like composition) portions
brownish. In living specimens, the body is seen to be divided
into 2 regions by a fold in the integument (any natural protective
covering, such as a skin, rind, or shell); the posterior portion
bears the last 2 pairs of the 4 pairs of very short legs. The
last 2 pairs of legs do not extend as far as the margins of
the body.
Life Cycle: Both sexes and all stages of the itch mite tend
to burrow into the skin immediately when placed on it, but
the nymphs and males make only small, temporary holes, and
move about frequently. The largest and longest burrows are
made by the egg-laying female. The female always burrows in
folds of the skin, preferring the deeper furrows and cracks.
She can be induced to enter when a fine scratch has been made
with a needle in the surface of the skin. She may also place
herself in the acute angle between a sloping hair and the surface
of the skin to gain support for initiating the burrowing (Heilesen,
1946). The winding burrow may reach a length of 5 to 15 mm.
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