Sifting, separating, and extracting
Many interesting, rare, and diverse kinds of insects live in rotten logs, leaf
mold, and other forest ground cover. In late fall and winter, numerous insects
seek shelter in these spots to overwinter. Searching by hand for them is
time-consuming, and small insects may go unnoticed. Several pieces of equipment
are available for removing insects from debris or soil:
[Berlese Funnel] [Flotation] [Separator Box] [Sifter]
The most efficient way to remove minute insects from soil and ground cover is
to use a Berlese (pronounced Bur-lazy) funnel.
This piece of equipment consists of a funnel with a screen placed about a third of the way down the length.
Heat, usually in the form of a light bulb, is applied either around the upper
portion or over the top of the funnel. A container of 70% ethanol is placed at
the small bottom opening. Leaves, debris, or other materials are placed on the
screen. The heat from the bulb drives the animals downward out of the debris
and into the container of ethanol.
This technique is used to collect eggs, pupae, and insects in other inactive
stages of development that live in the soil or among the roots of plants. Soil
and root samples are broken up in a container of water and stirred gently. Many
insects will float to the surface where they can be removed with a sieve or
filter paper
.
Another simple device used for removing insects from debris is an opaque
(doesn't allow light in) box with a tight- fitting lid to which is attached a
glass jar or similar collecting chamber
When a sample is placed in the dark box, those insects that are attracted to light will crawl or fly into
the jar. Because the separator box is often used to remove insects from debris
that accumulates in a sweep net, it is also called a sweeping separator.
Sifting is a good method for removing large, active insects from a sample. A
12-inch by 12-inch sieve about 4-6 inches deep with an 8 to 12 mesh screen
bottom works well.
Debris is placed in the sifter, which is then shaken over a
white surface (you may also use your beating sheet). The insects that drop out
can be picked up by hand, with an aspirator, or with a camel's-hair brush.
Insects that play dead when they fall can be spotted when they "revive."
A variety of sifters with different sizes of screening can be used. A kitchen
sifter can be used to extract smaller insects.
