What Temperature Kills Aphids? Here’s The Truth

Aphid populations seem to keep coming back every year, however hot or cold it may be. So it is natural to wonder: what temperature kills aphids? Let’s find out.

Aphids are tiny pests that feed on the plant sap of your precious plants and infest your gardens.

It is hard to get rid of them because they reproduce quickly and keep appearing back despite applying most pesticides or organic treatments.

Sometimes, you might not see them during the winter, but they will suddenly come back as soon as the summer/spring season comes.

This is because they either hibernate or lay eggs that can overwinter, hidden on the underside of leaves. While most aphids can survive summers, some become weaker and may die at high temperatures.

So what is the ideal temperature to kill aphids? Let’s find out.

What Temperature Will Kill Aphids?

Most aphids can survive hotter temperatures but cannot live in extreme cold. So how low should the temperature be to kill aphids?

Well, temperatures between 23 to 5 F are typically enough to kill them. On the other hand, some aphids may not survive in temperatures higher than 90 F.

If aphids are on healthy plants, they are able to fall down to the ground under the plant’s shade which protects them from high temperatures.

Research shows that in some species of aphids, such as pea aphids or green peach aphids, heat tolerance is governed by the Buchnera bacteria.

These aphids are associated with the Buchnera bacteria in a symbiotic relationship, and their tolerance to heat depends on which genetic variant of the bacteria they are symbiotes with (more about this later).

Can They Die When It’s Cold Outside?

Yes, aphids can survive when it is cold outside as long as temperatures don’t fall abnormally low. Some aphids show excellent cold resistance and are quite active in the winter months.

They lay eggs prior to the start of winters that can survive the coldest months of the year to hatch in spring or summer months.

Some aphids also have glycerol and mannitol (anti-freeze proteins) in their body that helps them to survive in the winter.

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Such aphids are more affected by hot temperatures. They show reduced activity and don’t procreate as much, either. It is easiest to get rid of aphids during the summer.

How Do They Survive in The Winters?

Aphids use a number of strategies to survive the winters, be it laying eggs in winter or dropping their body temperature.

• Male and female aphids breed in later spring, and the female lays eggs that overwinter. Most aphids survive the cold months as eggs.
• Some aphids reduce their rate of metabolism in winter like larger animals do during hibernation.
• Some aphids have body fluids that freeze, and their proteins get dissolved so as to avoid the crystallization of water inside the aphid’s body.
• Some aphids make their body temperature lower than the surrounding temperature to become resistant to extreme cold.

How Can You Kill Them in the Winter?

There are no specific techniques to kill them in the winter. If you are facing aphid eggs that are overwintering on your plants, you can introduce parasitic wasps that feed on them.

Another way is to clean the affected area with a solution of insecticidal soap. You can also spray natural insecticides on your plants, such as neem oil.

Another effective method is a biological control for active aphids feeding on their host plants. This involves introducing beneficial insects such as ladybirds which are predators of aphids.

Why Some Aphids Can’t Survive Summers?

Aphids consist of numerous subspecies. Some can survive the summers, while others can not.

To understand this, we need to understand the symbiotic relationship between some aphid species, such as Acyrthosiphon Pisum and a Buchnera aphidicola.

Both cannot survive without each other. Aphids provide shelter to the bacterium, while the bacterium provides essential nutrients to its host.

The bacterium produces two kinds of genes: one heat-tolerant gene and another heat intolerant. A single mutation can change the type of the gene, thus affecting the host organism.

Aphids that host bacteria without the heat-tolerant gene cannot survive in the summer. Many studies show that the bacterium dies when heat is applied. So, the host aphid fails to get the essential nutrients and dies or becomes dangerously weak.

Female aphids can reproduce asexually and can produce clones of themselves. Research shows that aphids exposed to high temperatures may not be able to reproduce.

Frequently Asked Questions

What kills aphids instantly?

You can make an alcohol-based insecticidal solution to kill aphids instantly.

You can mix equal parts of water and 70 percent alcohol in an insecticidal soapy water emulsion, or you can use store-bought chemical Insecticidal soap spray to kill aphids instantly.

Can aphids survive the heat?

Yes, some aphids can survive temperatures up to 90 F but may become weak in the summers.

Studies showed that the ability to survive heat differs for different species of aphids, and the temperature significantly impacts the aphids’ life cycle and metabolism pattern.

Do aphids lay eggs in the soil?

No, they generally lay eggs on the undersides of leaves or stems and secrete a sticky substance (honeydew) which helps to adhere the eggs there.

Even root aphids lay eggs on the plant, and once the nymph hatches, it can fall off into the soil. Some root aphids are known to burrow in the roots to lay eggs.

Why do aphids keep coming back?

Aphids have a life span of only 30 to 40 days, yet it seems impossible to control an aphid infestation. The reason behind the problem is the high reproductive rate of female aphids.

Aphid females can produce clones, which is why they can create as many as 12 copies of themselves a day.

Moreover, aphid eggs overwinter, and nymphs come out during the summer giving the impression that aphids keep coming back every year.

Wrap Up

You can kill aphids by exposing them to high temperatures. While some species can survive temperatures up to 90F, most will die or show become inactive at such temperatures.

Aphids can survive cold temperatures up to 5F. They can also survive colder temperatures by laying eggs, hibernation, and other defense mechanisms.

Over the years, our website, whatsthatbug.com has received hundreds of letters and some interesting images asking us about these insects. Scroll down to have a look at some of them.