Trapping
Collectors use a variety of traps and trapping techniques to capture insects
and other arthropods. These range from simple and inexpensive to elaborate and
costly. Some are designed to collect certain insects that are rarely collected
without a trap. Others are useful for general collecting. The traps and
techniques described here are just a small sample of those available to the
collector. A collector can invent new traps or modify old designs for unique
purposes.
The addition of bait to many traps will attract large numbers of certain types
of insects. Baited pitfall traps are common collecting devices. The bait is
placed in the bottom of the collecting can and covered with a screen, or it is
suspended into or over the trap. Dead animals, rotting foods, and dry cereals
are good baits for various crawling insects. One type of pitfall trap, the
cereal dish trap, is particularly effective for collecting insects attracted to
dung. This trap is made from a cereal bowl filled with 70% ethanol and sunk
into the ground. The bait is suspended in a small cup over the trap, supported
by a wire coat hanger.
When insects hit a barrier in their flight path, they tend to fly upward or
drop. Barrier traps placed in flyways rely on such behaviors to capture flying
insects. One simple barrier trap is the windowpane trap, which consists of a
piece of clear glass or plastic with a shallow trough filled with 70% ethanol
attached at the bottom. When the trap is hung across a path, in a flyway, or at
the edge of the woods, flying insects crash into it. Those that drop after
hitting the glass fall into the trough and are killed.
Immature insects live in a wide range of habitats, including plant stems and
roots, galls, rotting logs, decaying vegetation, soil, and water. When these
insects emerge as adults, they can often be captured in an emergence cage. The
cage can be as simple as a net sleeve over a tree branch or a screened box
placed over a patch of soil.
Light traps provide a good method for collecting large numbers of night-flying
insects or for collecting insects from several locations at once. They are also
a valuable tool for individuals who cannot be out at night to collect.
The simplest light trap consists of a UV light (often called a black light)
and a collecting pan with alcohol covering the bottom. The pan is placed below
the light, and insects flying toward the light eventually drop into the
alcohol. When set up near a stream or lake, this trap is very effective for
collecting the winged adults of many aquatic insects. Commercial light traps of
various designs are also available. Most of these consist of a light source, a
series of baffles, a funnel, and a killing jar. The jar usually contains
alcohol as the killing agent.
Another, more elaborate trap is the malaise trap, which captures flying insects
that move upward when they strike a barrier. This trap is a tentlike structure
made of netting with a collecting chamber at the top. Insects entering the trap
eventually fly or crawl upward while attempting to escape. Instead of escaping,
they become trapped in a killing jar or a container of ethanol. Malaise traps
can be purchased from commercial suppliers or constructed at home. A dark
fabric is recommended for the base. Malaise traps placed across paths or
alongside streams, woods, or sheltered clearings frequently yield good catches.
Also, when selecting a site, it is best to keep in mind that most insects fly
upward.
Insects that crawl about on the ground can be captured in a pitfall trap. The
simplest trap can be constructed easily by placing a can or plastic container
in the ground. Add enough killing agent (such as alcohol) to cover the bottom
of the container. To keep rainwater out of these traps, a board can be propped
up over the opening. Further modifications can change a simple pitfall trap
into a bait trap as shown above.
