Once sticky cards are placed in plastic bags, a marker can be used to highlight and count important insects.
For easy and "goo free" observation of insects on sticky cards, place the card in a clear plastic baggie. We use plastic zipper bags and cut off the zipper and cut open the two sides of the bag perpendicular to the zipper. This makes it easy to place the card between the plastic. When looking at a particular insect on sticky cards, you may need to examine more than one specimen of the insect because it may be stuck on the card in a way that masks critical structures for identification.
Frequently Encountered Insects on Sticky Cards
These are some common insect pests and natural enemies you are likely to catch on sticky cards in high tunnels.
Aphids are egg or raindrop-shaped. They can be many different colors, however, color is not a useful character for identifying aphid species. With the help of a hand lens, look for a set of 2 cornicles (commonly called "tailpipes") on the hind end of the body. Aphids can be winged or wingless.
Aphids on the underside of a pepper leaf. Note their body shape. Adults are about 1⁄8 inch long.
The arrow is pointing to a cornicle on a potato aphid. Photo: Kansas Department of Agriculture Archive, Bugwood.org
Thrips are shaped like a cigar, tapering at both ends. Like aphids they can be many colors.
Thrips and damage on a cabbage leaf. Note the cigar-shaped bodies. Adults are about 1⁄20 inch long. Photo: Whitney Cranshaw, Colorado State University, Bugwood.org
Whiteflies have wings that extend past their bodies. Two main types show-up on sticky cards in Pennsylvania high tunnels: greenhouse and silverleaf. They can be identified by the way they hold their wings with greenhouse whiteflies holding them flat and silverleaf whiteflies holding them pitched like the roof of a house, but this is difficult to see once they are attached to sticky cards. Looking for them resting on plants is the easiest way to see how their wings are held.
Greenhouse whiteflies hold their wings flat against their bodies and are 1⁄10 to 1⁄16 inch long. Photo: Whitney Cranshaw, Bugwood.org.
Silverleaf whiteflies hold their wings pitched like the roof of a house and are 1⁄10 to 1⁄16 inch long. Both photos: Scott Bauer, USDA Agricultural Research Service, Bugwood.org.
Fungus gnats are winged insects with 2 long antennae. They can be confused with Aphidoletes, a midge that is a natural enemy of aphids. When viewed under a microscope, fungus gnats have a Y-shaped vein on each wing and halteres (modified hind wings that appear as small knobs or clubs).
Look for the Y-shaped vein on fungus gnat wings. Photo: Whitney Cranshaw, Colorado State University, Bugwood.org.
Adult Aphidoletes midges or aphid predatory midges can be easily confused with fungus gnats, however, these midges lacks a Y-shaped vein. They are about 1⁄8 inch long.
Aphidoletes predatory larvae feed on aphids and other soft-bodied insects. They grow up to 1⁄8 inch long. Photo: Whitney Cranshaw, Colorado State University, Bugwood.org.
Shore flies may also be confused with fungus gnats. Shore flies are larger than fungus gnats and have stout bodies. Under a microscope, pale spots are seen on the wings. They also do not have Y-shaped veins on their wings like fungus gnats.
Shore flies are about 1⁄8 inch long. Note the pale spots on their wings. Photo: Jim Baker, North Carolina State University, Bugwood.org.
Parasitoid wasps are natural enemies. The key to identifying them is that they are very small, have a constricted waist and long antennae.
Parasitoid wasps are very, very tiny to about 1⁄2 inch long. Note the constricted waist and long antenna of this parasitoid wasp. Photo: David Cappaert, Michigan State University, Bugwood.org.
Parasitoid wasp next to an aphid mummy. Photo: David Cappaert, Michigan State University, Bugwood.org.
Lady beetles are another natural enemy. Adults vary in size and color, but are typically dome-shaped.
Lady beetle eggs can be found in clusters on the undersides of leaves. Adults are less than 1⁄4 inch long. Photo: Ronald Smith, Auburn University, Bugwood.org.
Crop-specific Insect Pests
Insect pest common to specific crops may also appear in on sticky cards. We are catching flea beetles and cucumber beetles in high tunnels with eggplant and cucumbers grown in them.
Flea beetles are small, shiny black and dome-shaped and less than 1⁄16 inch long.
Striped and spotted cucumber beetles
Striped and spotted cucumber beetle adults are yellow-green in color with either black spots or 3 black stripes on their backs.
Striped cucumber beetle adults are about 1⁄4 inch long. Photo: Gerald Holmes, California Polytechnic State University at San Luis Obispo, Bugwood.org.
Spotted cucumber beetle adults are about 1⁄4 inch long. Photo: Kansas Department of Agriculture Archive, Bugwood.org.
You will most likely encounter more insects than these, but these are the ones we are seeing most often. Your local Extension Educator can help with identification of others. Another resource is the Department of Entomology's Insect Identification Lab.
This article is part of a continuing series on scouting and identifying insects in high tunnels.