It’s probably accidental drownings rather than suicides. Just trying to get a drink, I suppose. In a natural body of water, they can drift to shore–but not in a pool.
As a kid I would rescue bugs from pools. I’m amazed at how much they can recover. honey bees can be lifeless and not move. But after you absorb the water from their spiracles, they (can) spring back to life and go about their business looking for nectar.
they’ll even clean themselves off with their limbs, looks kind of like a cat grooming itself, it’s so cute!
I’ll see if I can dig up the paper on this I read a long time ago, but as I recall it has to do with how they measure flying speed and distance to the ground.
Basically, they judge flying speed and flight elevation by watching how fast things on the ground go by. Higher up things pass by slower, lower down things go by faster, and this is used to judge height above the ground. Flying over a patch of still water (or a mirror in experiments) the insect has no frame of reference for its speed, so it drops lower and lower, eventually crashing into the surface, and, if over water, drowing.
And an english language summary of the original German paper:
- Heran & Lindauer 1963 Windkompensation und Seitenwindkorrektur der Bienen beim Flug über Wasser
As a point of interest, talking with pilot friends of mine they’ve said that something very similar can happen to humans flying planes and that you have to be alert for inadvertently dropping altitude and potentially crashing.
Thanks everyone above, glad to learn it’s an optical fluke rather than something more ominous… I used to think it had something to do with excessive pesticide use.
In hot weather honey bees need water, which they take back to the hive and use its evaporation to keep the hive at the correct temperature. If you would like to avoid them drowning in a pool, provide a shallow dish of water in a protected spot, with rocks or twigs in to enable them to escape if they do fall in.
In South Africa we have a project (Poolkill (s Afr) to document organisms killed or rescued from pools. I check my pool several times a day and of my contributions to this project I have only noted 27 observations (14%) as removed dead. In all other instances the organisms recovered.
They drown even in small cups of water, because they try to drink (or other insects, because they want to eat dead ones), I saw some of such drownings in act: they’re sure they will be ok, holding to the “wall”, but slip down in water.
Summer - hot - bees need water.
People have swimming pools, but only a few provide shallow water for wildlife to have access. Human and hardscape first.
When we stayed at Tankwa Karoo we rescued hordes of thirsty bees. PS WE added the stone so they had access!
Another cause is lights. The fly to the light, stun themselves, and then fall in. Have seen this happen many times. But like discussed before, there is no single cause.
If they get stuck in the water because they cannot climb the steep and slick walls to get out again, one way to help may be by providing some sort of ramp or float for animals to get a grip on. I’ve seen something like this being sold for frogs and imagine it might also work for bees. In shallower dishes, such as bird baths, you can add some rocks to create an island that allows bees to climb out.
It can be very helpfully for insects to have a watering station available. Fill a small bowl with pebbles and then just enough water so that the tops of the pebbles are uncovered. That way insects can land and drive with ease. I have several and when it gets really hot they are filled with pollinators.
I believe, from what I have read, that light reflected off of water is polarized, and that is something they can see, unlike us, and supposedly the polarization can confuse them in terms of their orientation.
The surface tension of water is strong for a small animal like a bee, and therefore it is difficult for an insect to escape once it is trapped in it.
Every day during the summer I rescue insects from the city pool at the end of my street here in Manhattan, and yes, a lot of them recover once they dry out, especially hard bodied animals like beetles.
I have also wondered whether the bees might be more attracted to pools because they are often blue or have blue components. Some species of bees are especially attracted to the colour blue.
Another similar phenomenon to this is why a lot of aquatic insects seem attracted to the roofs of cars (there was a study on this somewhere but I forget)
I’ve seen many dragonflies trying to oviposit on the roofs of cars on the road, for example
- Riska, et al 2006 Why do red and dark-coloured cars lure aquatic insects? The attraction of water insects to car paintwork explained by reflection-polarization signals
We reveal here the visual ecological reasons for the phenomenon that aquatic insects often land on red, black and dark-coloured cars. Monitoring the numbers of aquatic beetles and bugs attracted to shiny black, white, red and yellow horizontal plastic sheets, we found that red and black reflectors are equally highly attractive to water insects, while yellow and white reflectors are unattractive. The reflection–polarization patterns of black, white, red and yellow cars were measured in the red, green and blue parts of the spectrum. In the blue and green, the degree of linear polarization p of light reflected from red and black cars is high and the direction of polarization of light reflected from red and black car roofs, bonnets and boots is nearly horizontal. Thus, the horizontal surfaces of red and black cars are highly attractive to red-blind polarotactic water insects. The p of light reflected from the horizontal surfaces of yellow and white cars is low and its direction of polarization is usually not horizontal. Consequently, yellow and white cars are unattractive to polarotactic water insects. The visual deception of aquatic insects by cars can be explained solely by the reflection–polarizational characteristics of the car paintwork.
This topic was automatically closed 60 days after the last reply. New replies are no longer allowed.