December 9, 2010
Aphid mummies
Photo by Jessica Walliser

I was so excited to find these aphid mummies in my garden.

I finally finished cutting down and cleaning out our front perennial bed. I managed to fill three more tractor carts with leaves and other plant debris. It is such a good feeling when the garden beds are finally put to bed for the winter.

While I was out in the garden, I came across something very interesting that I learned about while researching my book, Good Bug, Bad Bug, but I never had the opportunity to see in my own garden. I was cutting down some stems of Heliopsis when I noticed that there were hundreds of orange aphids all up and down the stem. 

They were kind of beautiful, in a weird way, so I looked a little closer. Then I noticed that at the top of the stem were all these aphid mummies. The mummies are called such as they are just the exoskeleton of the aphid after a teeny tiny parasitic wasp called the aphidius wasp has parasitized it. The adult female wasp is so tiny that she can lay a single egg on the back of an aphid. The egg hatches and the resulting larva tunnels into the aphid, eating it from the inside out. The wasp larva eventually pupates into an adult while still inside the aphid, all the while turning it into a mummy. When the adult wasp has matured, it chews a perfect round hole in the back of the aphid mummy, emerges from it and flies away. And here, right in my very own garden, were a bunch of aphid mummies—and coming out of the back of one of them was a wasp! Sooooo cool to see.!

Of course, I ran inside and grabbed my camera to take a few pictures. They aren’t as close as I would like, but you can get the idea of what this is all about.  If you look carefully, you’ll see the brown aphid mummies and a small black wasp with clear wings.

Here is the biggest lesson to take out of this: If I had sprayed the aphids with a pesticide, blasted them off with the hose or even squished them with my fingers, I would have been killing all these beneficial wasps preying on them. Understanding how beneficial insects work in your garden is so very important to maintaining a healthy balance of both good and bad bugs.  How fun to see the whole cycle in my very own garden—and in December none the less! 

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