Aphids in the sky and underground

It’s spring! Well today is the first day that feels like summer, but it’s spring. In places where plants die back in the winter, spring is a full of new growth. And lots this new plant growth seems to miraculously get covered in aphids. Where do they come from?

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While some of them may already be in your plants, hitting as eggs, some literally fall out of the sky. It’s a strategy for finding new habitats. It’s amazing really. Aphids drift on the wind, high up in the atmosphere until they fall down to earth. A collection of insects at 30,000 ft found a substantial amount of aphids (and a certain type of spiders).

The chance of landing on your rose might seem infinitesimal, but there are millions of aphids floating around in the atmosphere. If only one lands on your rose, you’ve got aphids. As I discussed in a previous post (https://wordpress.com/post/getbuggy.wordpress.com/51), aphids reproduce by cloning themselves. So just one female can populate the whole garden over the summer.

But aphids are not just on the surface and in the air. They are also underground! Just like there are aphids that attack leaves, there are aphids that attack roots. They suck the juices out of the plant in the same way (see https://wordpress.com/post/getbuggy.wordpress.com/51 for more details on aphid feeding), but they do it underground.


Root aphid on a root

This is particularly sneaky because you don’t know that they are draining resources from the plants. Plants with root aphids can have reduced vigor, wilting, and fewer flowers/fruits.

Then when it gets crowded down below, they can come up and feed on the leaves. So then you have aphids everywhere.

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Root aphid on a leaf

So what should you do about root aphids? There are several fairly effective, non-toxic ways of treating root aphids. One is the same treatment that I like to use for fungus gnats (https://wordpress.com/post/getbuggy.wordpress.com/325), predatory/beneficial nematodes. There are several species or combinations of species available on Amazon and in many garden stores. They should all work fine. They do need to be stored in a certain way and kept cold during shipping to be alive and effective.

Another way to deal with root aphids are entomopathenogic micro-organisms, mainly Beauveria bassiana. B. bassiana is a fungus that attacks insects. I’ve had the most success with a product called Mycotrol (http://www.bioworksinc.com/products/mycotrol-eso.php). The fungus spreads out through the soil and gets inside the insects. B. bassiana and similar organisms are part of the soil. It’s one of the reasons that maintaining healthy soil is so important. Because while I love aphids, I (and you probably) don’t always want them on my plants.

Happy spring!



About keviclaire

I recently graduated from the Department of Environmental Science, Policy and Management at UC Berkeley. My research interests are focused on biological control and how to increase it's use in agriculture and home gardens. I am also an avid gardener and insect photographer. I'm using this blog as a place to share those interests!

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