[belly_joe]

Is there a way to check local insect levels without harming their populations?

A lot of comments in here have been anecdotal observations of pretty big population swings and I too (in the northeast of the USA) have noticed the insect populations have increased over the past two years after a nadir in prior years, but I have no real way of determining what's going on scientifically.

Wondering if anyone has experience doing something like this: https://rodaleinstitute.org/science/articles/how-to-monitor-...

[murphyslab]

It's a fairly common concern, however in the view of entomologists, the number of individual arthropods killed is generally a drop in the bucket. Moreover, many species cannot be identified without detailed examination. As one entomologist explains:

> In addition, a lot of important insect parts need to be extracted for species-level identification. Often the methods required for this aren’t possible to perform on live insects, and when they are they often injure the insects anyways. > https://askentomologists.com/2015/01/01/why-do-entomologists...

Personally, I've tried to identify certain fly species using several high quality photographs taken from multiple angles, however at best one might get the genus; figuring out which species it is often requires direct access to the insect and may even require dissection in some cases. This was the case when trying to figure out exactly what species of horse fly was attacking me while out hiking. Even with a decent key, provided by the Canadian Journal of Arthropod Identification, I couldn't get a definitive answer on the specific species. (cf http://cjai.biologicalsurvey.ca/t_13/t_1321.htm )

And on iNaturalist.org, a citizen science project based on automated visual recognition (using user-supplied, geotagged photos) and often the participation of expert identifiers, many insect species have never been ID'd even once. And that's a combination of the issues of rarity (and perhaps species loss) and the challenge of visual identification. In one family in Order Diptera (flies) that I examined, less than 1/3 of the Genuses had any observations, and in one of the genuses that did have a decent number of observations, those were assigned to only 12% of the species in that genus.

So there are strong limitations to what we can do without harming individual insects. Nonetheless, these sampling and identification methods don't substantially harm insect populations.

[ianai]

Stamets is hoping to make smart bee feeders eventually to help count them while nurturing their populations too:

https://fungi.com/pages/bees

[Someone]

The search term “insect counting device” gave me many hits, for example https://link.springer.com/article/10.1007/s00340-019-7361-2:

“We have constructed two optical sensing systems for insects based on light attenuation and light backscattering, respectively. The systems, which were tested with the potentially dangerous Aedes albopictus and Culex pipiens, were able to extract the wing-beat frequency, when they passed impinging light, derived from light-emitting diodes. We could achieve distinction between the sexes of A. albopictus and C. pipiens based on the wing-beat frequency”

https://www.hindawi.com/journals/js/2018/3949415/:

“We present a novel bimodal optoelectronic sensor based on Fresnel lenses and the associated stereo-recording device that records the wingbeat event of an insect in flight as backscattered and extinction light. We investigate the complementary information of these two sources of biometric evidence and we finally embed part of this technology in an electronic e-trap for fruit flies. The e-trap examines the spectral content of the wingbeat of the insect flying in and reports wirelessly counts and species identity“

I also would think the number of insect deaths by scientist-placed insect traps would be dwarfed by both that of traps placed just to kill insects and ‘traps’ formed by the area of car wind shields being swiped through the world.

[jimmaswell]

I've heard the correlation of bug splatters on windshields a lot. Apparently used to happen all the time, now more rare.

Looks like it has a wikipedia article: https://en.m.wikipedia.org/wiki/Windshield_phenomenon

[rootusrootus]

I got downvoted to oblivion a few months back for suggesting that maybe cars were just getting more aerodynamic. I still wonder if anybody has really considered that. I assume so, it seems like a plausible first guess.

[sulam]

I have a car that's not very aerodynamic (Jeep Wrangler) and when I'm driving through rural areas the insect mess at dusk or dawn is bad enough that I have to run the windshield wipers. Conversely, I never have to worry about it around my house, which is in the middle of large urban area (SF Bay Area).

Now, consider that there has been massive human migration into urban areas over the last century, plus cars getting far more aerodynamic in the last 40 years, and I think you can make a case for observation bias. However, I think you can also say very firmly that urban areas = less insect populations, so as our urban footprint grows, it is likely costing us. I think suburban sprawl may be even worse, because of the habitat destruction your typical housing development causes without the benefits of density that a truly urban environment offers.

So honestly I think you could be right and wrong at the same time. It is definitely worth correcting for.

[nathanmcrae]

Interestingly, this article [0] states that the opposite is true: "The research included vintage cars up to 70 years old to see if their less aerodynamic shape meant they killed more bugs, but it found that modern cars actually hit slightly more insects."

[0]: https://www.theguardian.com/environment/2020/feb/12/car-spla...

[refurb]

The UK study mounts a grid where the license plate goes which doesn’t necessarily disprove a change in aerodynamics for bigs hitting the windshield.

[rootusrootus]

That seems plausible. Perhaps an car with poor aerodynamics pushes a wall of air in front of it that deflects bugs up over the car, where a slippery car may allow the bugs to smash right into the glass.

Now that I've made my comment, I'll go read that article. Thanks for sharing ;-)

[makerofspoons]

With a decent (perhaps high speed?) camera and a trained computer vision model, couldn't a contactless study be performed of flying insects? It should be possible to count the common species in an area with reasonable accuracy and flag photographs of unknown species for human review. Definitely not as cheap as a trap, but perhaps with solar power could be just as easy to place. Unless someone with experience with these studies can make the case that the number of insects killed by these traps is negligible and all this effort isn't worth it of course.

[veddox]

The problem is you simply cannot identify most insect species from photographs of them flying. Depending on which taxon you're working on, you have to do things like count the number of tarsi (foot segments) on each leg, look at the vein pattern on their wings, count the hairs on their thorax, or other minutiae. Also remember that most insects are only a few millimeters in size.

Some taxa can readily be identified in the field (butterflies, most grasshoppers, some beetles and true bugs). Others (dipterans and hymenopterans and pretty much anything smaller than 5mm) need to be done in the lab, with a good stereoscope and big identification books. It helps to have a steady hand and lots of experience...

(In fact, several taxa are so difficult to identify down to the species level that there might only be one or two experts in the whole country that can reliably do so.)

[giardini]

belly_joe asks: "Is there a way to check local insect levels without harming their populations?"

Hire a Buddhist to go camping and keep a log of bites/hour.