Study summary
Density and Diversity of Nontarget Insects Killed by Suburban Electric Insect Traps
Frick TB, Tallamy DW
Read the original paper- Study type
- Field Trial
- Year
- 1996
- Published in
- Entomological News (1996), 107(2):77-82
- Evidence strength
- Well-supported evidence
Summary
This study looked at what suburban bug zappers actually catch. The researchers collected and identified the insects killed by electric zappers over a summer in residential settings, then sorted them into groups: biting flies such as mosquitoes and biting gnats, harmless non-target insects, and beneficial insects. The point was to test the everyday assumption behind buying a zapper for mosquito control, namely that the insects crackling on the grid are the ones that bite you.
Key findings
Of 13,789 insects killed and identified, only about 0.22 percent were biting flies such as mosquitoes and biting gnats, while roughly 48 percent were harmless non-target insects, and the remainder included beneficial and other insects. In other words, the trap was killing thousands of insects, but almost none of them were the ones that bite people. This is the honest core of the zapper debunk: the device genuinely kills insects, yet it does little to reduce mosquito bites and it removes large numbers of harmless and beneficial insects in the process.
Limitations
This survey characterized what zappers catch rather than directly counting how many bites a nearby person avoids, though the near-absence of biting flies in the catch speaks for itself. Catch composition can vary with location, season, and whether a carbon dioxide or octenol lure is added, and a lure can raise the mosquito share somewhat. Even so, the central finding that zappers overwhelmingly kill non-biting insects has held up as the standard reason entomologists advise against them for mosquito control.