Entomologists often collect night-flying insects using a black light and sheet. The black light is suspended in front of a white sheet. Insects attracted to ultraviolet light fly toward the light, and alight on the sheet.
Professional night collecting equipment often consists of a durable white sheet attached to a collapsible frame, constructed from aluminum tubes like to the frame of a camping tent. The black light is suspended from a cord running from the top of the sheet to the ground, or is mounted on a tripod on one or both sides of the sheet. For an amateur insect collector, purchasing this equipment can be expensive.
You can make your own night collecting equipment to save money. While your homemade collecting equipment might take a little longer to set up, it will work just as well as equipment purchased commercially. You will need:
- a length of rope, long enough to span the width between two trees in your chosen collecting area
- a black light
- an old white sheet
- clothespins (optional)
- a power source for your light, if it's not battery-operated
Tie the rope so it spans between two trees, at about eye level. Make sure you tie it securely, so it will hold the weight of your sheet without drooping. Drape the white sheet over the rope, allowing 1-2 feet of the sheet to lie horizontally on the ground. Some insects prefer to land on vertical surfaces, while others like horizontal surfaces. The latter group will collect on the part of your sheet that is lying on the ground. If your sheet is not long enough, you may need to attach the sheet to the rope using clothespins to allow extra length on the ground.
Black lights sold by science or entomology supply companies tend to be more rugged and last longer for outdoor use. You may be able to buy a less expensive black light from a discount or party supply store. If you don't have a black light, you can use an incandescent light, a portable fluorescent light, or even a camping lantern, and still get a good result.
Suspend your black light in front of the sheet, near the top. You can tie the light from a branch using some extra rope, or run another length of rope between the trees and attach the light to it. If you use a battery-operated light, you will have more flexibility in locating your collecting sheet. A light that uses AC power may require a long extension cord.
At dusk, turn your light on. Monitor the sheet periodically, checking for interesting specimens to collect or photograph. You can use forceps or an aspirator to collect moths, beetles, or other insects that land on your sheet without damaging them.