I used seven ways to estimate insect population sizes before and after an aerial spray application of Malathion insecticide. Those were to sample the insects likely present during the daytime.
Some insects are not active during the day and cannot be sampled by sweep nets, molasses traps, sticky-board traps, extraction from soil, etc. I needed to sample at the center of two woodland areas at night, then to repeat the sampling when one area had been sprayed, then to make the comparisons.
I purchased a light trap, one with a “black-light” or ultra-violet-fluorescing bulb. It was large and bulky and I needed a power source in the center of the forest. I had to build a carrying box, find large wheels suitable for easily rolling over limbs and logs in the forest, find a “converter” to change DC to AC current from the 12 volt auto batteries, and then go and sit in the silence of the forest alone in the purple of the night watching insects hit the baffles and fall into the poison at the base.
These were nights of reflection about sampling errors, about adequate sample size and about whether “a little knowledge may be better than none” … unless the sample is too small. On these nights I discovered yet-un-named insects and surrendered to my doubts that I could understand and model a system with things in it about which I (or anyone else) knew nothing and had met for the first time.
I did not catch enough mosquitoes. They were concentrating on me. I was especially concerned about their attacks for I had taken a class in Medical Entomology from Dr. Carl Venard at The Ohio State University. There seemed to be danger in every buzz. I caught beautiful moths … and I was sorry for their loss. I caught many adults of the “inch-worms,” the forest leaf eaters also called “millers.”
Of course there were differences in insects caught before and after the spray, but the differences were confounded by extreme differences in numbers trapped between areas, between years, between nights … just another expensive study confirming ecological variability and raising doubts about whether the much-touted “comprehensive knowledge of the functional ecosystem” can be achieved.