Diving beetles showing up mysteriously

About a year ago, I placed a large tub in my yard to see what insects I could find in it. A month later, I noticed several mosquito species, crane fly larvae, tadpoles, and diving beetles. This made me wonder how the diving beetles got there.

I am not a beetle expert, so I do not know how this could be possible. Please let me know if you know how this happens.

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They fly. They’re quite a common bycatch in moth traps too.


Thanks! That makes much more sense.

I came back from leading a bird walk a few years ago, and all the cars in the parking lot were covered in dead water boatmen (which are bugs, not beetles, but are also aquatic). They had been flying and were tricked by the reflective paint of the cars, so they landed on them and died due to heat. It was pretty sad.


Diving beetles are very mobile and the cranefly larvae, mosquito larvae and tadpoles are all fodder for them, depending on their size. In creeks that dry out seasonally in Australia, they will fly to remnant pools and can be found in huge numbers in puddles that are too small to accommodate larger predatory fish. (They’re still in the larger remaining stretches of water, just not in such high numbers because their predators are still there too.)


The flying beetles see the reflection of the light on the water surface (or my dark-colored truck apparently) and dive on in (or go splat as the case may be).

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I’d never heard of diving beetles until after setting up a moth light. Had no idea what they were when they first showed up! I presume they came from bodies of water on neighbouring properties.


I’ve never tried making a moth trap. I wonder what else they could attract besides moths.

In my experience, they attract various beetles, mayflies, stoneflies, and chironomids. Not as many as the moths, but those are often in my traps.


I don’t have a trap as such, just a sheet and a light. I created a project for everything I find, which is here:
I’ve had various types of beetles, flies, ants, mantises, katydids, treehoppers, lacewings, crickets, grasshoppers, spiders, and even frogs show up. The frogs come to eat the moths. The most bizarre one possibly was when I turned the light on a bit too early, and a kookaburra showed up to grab anything the light attracted. https://www.inaturalist.org/observations/195827249
Now I wait until it is quite dark and the birds have gone to sleep before turning on the light!


Parasitic wasps, nocturnal velvet ants, winged ants, flies, midges, beetles, mayflies, caddisflies, grasshoppers, lacewings, leafhoppers, plant bugs, and antlions. Probably a few more I’m forgetting.


Wrens. If you aren’t up early enough to take the trap in, you might be left with just detached wings.

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