Low-Cost Automated Flight Intercept Trap for the Temporal Sub-Sampling of Flying Insects Attracted to Artificial Light at Night

In the study of light pollution, you need to sample between dusk and dawn. Our low cost automated flight intercept traps enable the capture of flying insects at user defined intervals. Sampling multiple sites simultaneously can be difficult because you need to have researchers located at each site to start and stop your equipment simultaneously.

This trap can be used in any ecological study on flying insects that requires greater temporal or spatial resolution, which cannot be provided efficiently by other sampling techniques. An example may be circadian or seasonal patterns of activity. No specialized skills are required to build this trap.

You just need to be comfortable using simple workshop tools. Begin by cutting the polycarbonate roofing sheets with a jig saw. Then, cut an eight millimeter center groove halfway up the center of each pane.

The two panes can now slide together to form a cross baffle. Slide the cross baffles snugly into the plastic funnel opening. Secure them to the funnel with 20 millimeter stainless steel angle brackets by drilling holes while the angle brackets are in place.

Then use M4 screws and nuts with washers to secure the cross baffles to the funnel. Cut another piece of the polycarbonate sheeting from the remaining sheets. Drill holes and secure the piece at a 90 degree angle to the top of the cross baffles to form a protective roof using 20 millimeter stainless steel angle brackets, M4 screws, nuts and washers.

Trim the funnel spout to a length of approximately 30 millimeters with a hacksaw to ensure that the sample trays of the automated pet feeder will rotate unobstructed at the programmed intervals. Place the automated pet dispenser with a nine liter and 30 millimeter diameter plastic basin to protect the samples from weather conditions. Drill a 20 millimeter hole into the top of the nine liter basin and place the funnel spout into the hole to position it directly above the sample tray.

Using a drill with a hex head driver bit secure the plastic basin to a 500 millimeter piece of treated pine fence paling with galvanized hex head screws. To stabilize the entire trap for hoisting into the air via ropes, attach a wooden stake to the piece of treated pine fence paling with an angle bracket and tie wire. At the sampling location, remove the automated pet food dispenser from beneath the plastic basin.

Then, open up the pet food dispenser and place foil dishes containing soapy water, or a preservative of choice, in each food tray. Set the clock time and then program each pet food dispenser tray to set the food tray rotation times by following the directions provided with the automated pet food dispenser. Place the food dispenser back underneath the plastic basin.

Secure the basin to the timber fence piece with the galvanized hex head screws. Attach a rope to the top of the trap with a carabiner. Then, hoist the trap into position using a ladder and secure it beneath the experimental lights by the carabiner.

Attach a second wooden stake to the tree with an angle bracket to stabilize the trap in high winds. After the trap sits on top of the stake, secure it with two long cable ties. To collect the insect samples, lower the traps with a rope, remove the automated pet food dispenser from beneath the plastic basin, then remove the lid of the pet food dispenser and lift out the aluminum trays.

Finally, pour the contents of the trays into the pre-labeled sample vials. A comparison of relative capture efficiency of various flight intercept traps is shown here. In the present study, a total of 488 flying insects were captured over three sampling days at four sites.

Two types of traps were examined in this study. Traps placed under lights and those without experimental lights. A total of 16 traps were installed, among which 12 were with experimental lights and four were without experimental lights.

The number of trap days, which is equal to the number of traps multiplied by the number of days, is 36 for the traps with experimental lights and 12 for the traps without experimental lights. Therefore, to evaluate the efficiency of the traps, the total number of arthropods collected were divided by the effective surface area of each trap and the number of trap days on which they were operated. Traps perform similarly to other multidirectional baffle style traps under lights and without lights.

Hence, the traps appear to be as effective as traditional flight intercept traps, but with the added benefit of sub-sampling at user defined time periods. Each collection tray holds approximately 330 milliliters which will accommodate most applications, but it would be beneficial to test the traps during swarming events.