Water can work to rid your plants of aphids, but is this because they drown in water or because of another reason? And can you drown aphids effectively or not?
Aphids can drown, but this relies on them being fully submerged underwater for an extensive period of time – usually 24 to 48 hours. Aphids can actually store large amounts of oxygen making it hard to drown them.
Can Aphids Drown?
If they are fully submerged in water, then yes, aphids can drown.
Although insects have different breathing mechanisms to humans, it is technically closer to suffocating rather than drowning. But the main point is that yes when fully submerged in water, aphids will die.
Does Water Kill Aphids?
The mere presence of water will not kill an aphid. They are exceptionally resilient insects and will not be killed on contact with water.
They do not appear to have a particular like or dislike of the liquid, but it can be dangerous for them in large or powerful quantities.
Can Aphids Swim?
It does appear as though aphids can swim or at least float. This is why drowning them is sometimes not the most effective method of removing aphids, as many can escape their fate by using the water to travel.
If there is a large enough volume of water and a way to keep them fully submerged, then they will drown and will not be able to swim away.
How Long Can Aphids Survive Underwater?
Underwater, aphids can survive for longer than you think. Going back to their breathing mechanisms, as an insect, aphids can store oxygen in their exoskeleton without actually using it.
This means that if they have a large amount of oxygen stored before being submerged, they will survive for a surprisingly long time underwater. They can survive for a couple of days in some cases. The problem is, if you don’t kill every aphid then the colony will recover and before you know it your infestation is back!
This is another reason why water is not the most effective method of killing aphids living on your plants. That being said, water can still be used to quite a strong effect to remove the aphids from their places on your plants.
Can Aphid Eggs Survive Underwater?
There is little confirmation on this; however, it does appear as though aphid eggs will not survive if submerged underwater.
They are quite hardy as many eggs can overwinter, and the nymphs often hatch quite quickly, so some may resist the submersion of the water.
That being said, as the aphid nymphs will have not been able to store any oxygen, if they do miraculously hatch, then they will proceed to drown.
Will Submerging Plants Kill Aphids?
If aphids can drown, then one way for you to kill them may be to submerge the plant’s afflicted area into the water for a long time. Unfortunately, you’ll need to submerge some plants for at least 24 hours for it to be effective.
However, you shouldn’t do this.
As mentioned earlier, aphids can store oxygen, so there is no way to guarantee that you will kill all of the aphids that reside on the plant.
Even if you could, submerging the plant in water like that for an extended period of time would cause some severe damage to the plant. All in all, for a method that is not guaranteed to work, it simply isn’t worth it.
Can Water Be Used to Remove Aphids?
Despite this, you can still quite easily remove aphids from your plants by using only water.
Using a hose or a spray bottle of some kind can remove aphids. If the blast is powerful enough, merely spraying the aphids on your plants will dislodge them and their eggs, leaving your plants aphid-free.
However, you should then take extra precautionary measures to prevent them from coming back.
The other thing you can do is to combine water with a few drops of washing up liquid to spray your plants. This can help remove the aphids but can also ruin their waxy outer coating making it more difficult for them to cling onto your plants.
To summarise, fully submerging in water will cause them to suffocate and drown.
Submerging a plant in water to kill aphids this way is a bad idea as it can also damage your plant. Especially seeing as you’ll need to submerge the plant for several hours, maybe even overnight.
Aphids can store oxygen, so some can survive underwater for quite a long time. If you want to use water to treat your aphid problem, then the best thing to do is use a high-pressure hose and spray them to dislodge them and their eggs.
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Ryan is a keen gardener from the UK who’s spent years dealing with countless, common pests over the years so knows the ins and outs of how to deal with pests in the garden