What are good homemade insect traps?

I have used traps for insects for over 50 years.

  1. Simple bottle trap uses a straight side jar or one with a shoulder. Lightly vaseline the inside 1-2" using real Vaseline which is very slippery and wipe it off making the glass inside neck and lip un walkable by any insect. Put some food/banana or water source in the bottom. Many insects are seeking moisture. If you want burying beetles and flies put a dead mouse in the bottom. Bury it up to its neck in the ground and put some bark or a board over it to screen it from rain. Check it daily.
  2. Moth bait made from molasses/brown sugar/stale beer/ mashed ripe banana is mixed into a thick cocktail and paint it on some trees along a well known path before dusk. Use a lantern and bring a wide mouth jar with you and patrol the path and shine your light on the the painted spots on the trees. All sorts of moths, ants, beetles and wild cockroaches (usually the flying males) will be feeding on the bait. You will find wild cockroaches, which are very delicate and beautiful, all the way up into Canada. Enjoy the evening walk and collect them with the wide mouth jar placed over them for closer examination. You may collect some of the underwing Moths viewable in Legion of Night
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You can extract arthropods from leaf litter by putting some on a mesh or wire frame and placing that midway down a collection container. Then shine a bright light from above to heat the top. The light can be strung through the top of the container (to keep it sealed), or the container can be transparent on the top. Or a funnel can be used to hold the leaf litter with the bottom hanging in a bottle. With no cap, more will escape than otherwise would, of course.

If you take too much litter you get a lot of bugs and it’s therefore not exactly harmless since you don’t know where they came from to put them back. But plenty of them seem to live, so it is not maximally destructive, either, and you can scale it down to as much litter as fits into a large funnel. You do need to get a good amount litter to have a chance of finding something inside it, since you get what migrates downwards from the light, so sample with that in mind and you’ll be good.

The setup is called properly a Tullgren funnel, so you can look it up. It grabs spiders, beetles, beetle larvae, springtails, millipedes, anything that lives in the soil and leaf frass.

If this fails, hit the bush with a sturdy, long-handled net. Then carefully inspect the net, not letting the fly out till you’ve seen them. This will harm a bush which is not sturdy itself: use judiciously.

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Here’s a link to the Oregon North Coast Land Conservany blog:
https://nclctrust.org/mothing/

I have since installed a more or less permanent “moth wall” made of plywood and painted flat white in place of the sheet with hooks to replace the lights.

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Here’s one I made for attracting rare sand dune beetles. They don’t fly but are attracted to UV lights. The tripod is a basic one with a hook on the central post, the tube is a plastic core from a roll of plotter paper and the lights are white and UV led ribbons from Amazon. I think the lights, switches, and a 12V RV battery cost about $50. We set it up on a large white sheet and all kinds of insects come to it.


There’s a rope through the middle of the tube to hang it and separate switches for the white (yellow when turned off) and UV (silver when turned off) lights.

The bottom has a power plug. When it’s windy I put a rock on the cord to keep it from swinging.

It fits inside a poster tube for easy carrying and to protect it in the car.

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https://bughunter.tamu.edu/collection/collectionequipment/trapping-insects/ has some general ideas. Adding a funnel shape to the top of your solo cup would greatly reduce the number of escapees. Capture shows a specialty trap that includes such a funnel in the lid. Also a section of pipe protruding into a larger capture area has a similar effect.

There already appear to be incredible explanations of different traps you can use on this thread. You may also enjoy looking through this web page here: https://mississippientomologicalmuseum.org.msstate.edu/collecting.preparation.methods/Collecting.methods.htm#.Ws0Uf2kpC7M

I mainly use a light trap. I put two chairs in my backyard next to each other, place a blanket over them, place a blacklight and a UV tube (former reptile light) under or clipped on the chairs, and turn them on at night.

What do you folks do to associate your light trap observations with particular wavelengths?

I’ve started using UV and visible lights that peak at particular wavelengths, and have noticed differences. E.g. the shorter the UV, the smaller the moths, and the more ground beetles come to the light. So I’d like to note which wavelength I used. Are there fields for this in general use?

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The blog post I linked to in my question above suggested this field: https://www.inaturalist.org/observation_fields/3387

And I knew about this blog, but never noticed the field suggestion. Thank you.

I started playing with the light sources that @damontighe suggested there, and they work well enough. But since I didn’t plan to travel, and had a LED plant grow light sitting at home, I tried that as well. I looked at it with a spectrometer, and it has peaks at 398, 448, 540, 631, and 737 nm – all over the spectrum. It’s brighter and I’ve had a lot more success with it than with the UV only sources. So that seems to be an option if it doesn’t have to be portable.

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i read somewhere that insect vision starts to phase out around 550nm to 650nm (yellow to red) and ends on the other end at around 300nm. i use a 365nm light as my UV source, and it does seem to attract mostly small insects. if i add a white light (which should have a mix of other wavelengths), i attract other things. i’ve been thinking about getting a 395nm light, since i read somewhere that 400nm seems to be the best wavelength for attracting a wide range of insects.

Oil of wintergreen will bring in halictid bees!

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That is a thing of beauty.

Yellow pan traps are simple and effective for bees/wasps/ants and also flies. A yellow plastic bowl or deep plate filled with water and a drop of dish detergent is effective, but you can always leave them empty if you dont want to kill anything. Just catch whatever turns up in a jar for observing/photographing.

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Plastic red solo cups, as you mention, are pretty good as pitfall traps for terrestrial arthropods. I first saw them used this way in a capture-recapture study of scorpions out in the desert. If you nest one inside another, you can easily remove the inner cup to check its contents and then re-seat it in the buried outer cup. An elevated cover board is probably a good addition.

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I got a complaint about my plain old fluorescent tube light trap in my urban setting. Are the black light, UV lamps less offensive to neighbors who, for whatever reason, are trying to get some sleep? :confused:

How do they get on with cars driving by with headlights on?

my understanding is that the best wavelength for attracting insects is about 400nm, which is just within the human visible spectrum. i think most UV lights wouldn’t be able to produce a narrow spectrum, unless they’re filtered, which is expensive. and you probably wouldn’t want to go much below 365nm (just outside human vision) because it starts to get nasty at that point. so given all that, i would think any UV lamp that would attract insects would probably be noticed by your neighbors, too, if they notice your regular fluorescent tube light (assuming same output).

This wasn’t intentional but I’ve found that an empty flower pot under my porch light always contains a collection of beetles in the morn

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Thanks, @pisum I think I will try a light in that range and see if it’s more tolerable. For what it’s worth, the complaint came from within my own house and to be honest even with the shade pulled and being on the second floor I found the glow intrusive myself.

just note that the insects you attract at 400nm (ex. large moths) may be different than the insects you attract at 365nm (ex. flies). also note that if your shades are cloth, they may fluoresce and glow brightly (in the visible spectrum) when exposed to UV light.

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