a handbook of the mosquitoes of north america - Systematic Catalog ...

80 MOSQUITOES OF NORTH AMERICA
which can be easily removed. When removed, nets fitted on
brass rings of various sizes can be screwed in and co,llections
of larvae or adults made whenever desired. The water nets are
small and can be carried with ease. The air net is so made that
it folds together when removed from the cane. By inserting
the permanent screw, the cane is very useful in tramping over
hills, marshes, bogs, etc.
Prcserz~ation ,o f Larvae
The simplest method of preserving larvae is in 85 per cent
alcohol. Kill directly in the alcohol and transfer to small vials.
Do not atte’mpt to kill too many larvae at once as the larvae
will wriggle so much that many hairs, spines, etc., will be lost.
In order to prevent the loss of hairs, etc., which easily rub off.
place a small amount of loose cotton in the vials, to prevent
shaking. The ideal method of securing larvae for future study
is to bring carefully collected specimens to the laboratory.
There they should be killed a few at a time in water just at the
boiling point. Of course only fourth stage larvae should be
selected. Do not leave in the hot water more than a few
minutes. Transfer to 50 per cent alcohol for 24 hours, and then
to 70 per cent for the same time and store in 85 per cent alco-
hol.
The larvae should be mounted for study unless you are a
specialist and can readily identify them by examination in the
alcohol. The larvae should be dehydrated in 95 per cent alco-
hol, in 100 per cent alcohol and then mounted directly in
Euparal, a substance that gives permanent mounts and also
clears the specimens. If Euparal is not available clear in carbo-
xylol, oil of cloves, etc., and then mount in Canada balsam. In
order to secure the best mounts so as to see all the characters
used in descriptions the writer adopts the method of cutting the
larvae just in front of the eighth segment. This is done either
when the larva is in 100 per cent alcohol on the slide or after
adding the Euparal. The cutting can be done with fine dissecting
needles as the larva is then very brittle. By this means one