90 percent, and 95 percent. The choice of aIcohol concentrations and the sequence of
dehydration are dependent on the delicacy of the specimen. For example, specimens
with soft-body walls wiII not collapse if processed gradually through the entire alcohol
series in ascending order of concentration. Specimens with hard integuments can be
dehydrated by placing them directly into high alcohol concentrations without causing
any damage to the specimens. Following the dehydration series, the specimen should
be rinsed in xylene that is miscible (capable of being mixed) in permanent mounting
media.
a. Preliminary Procedures. Preliminary procedures for permanent mounts are
the same as those described for temporary mounts. There are several permanent
mounting media available. Canada balsam is probably the most widely used. After the
desired media has been selected, the mounting procedures are conducted in the same
manner as described earlier; however, permanent mounts should' be dried at 50 C for
two weeks.
b. Correct Mounting Positions. For easy examination, specimens mounted on
slides must be properly oriented.
(1) Fleas are placed ventral side up with the head to the right. Lice,
bedbugs, and mites are placed ventral side up, with the head pointing down, toward the
mounter. If desired, two specimens of the same species may be mounted on one slide-
one with dorsal side up, and the other with ventral side up. Correct mounting position for
a flea, a louse, and a mite are shown in figure 4-7.
LOUSE
MITE
Figure 4-7. Correct mounting positions for a flea, a louse, and a mite.
MD0170
4-11