Please excuse the rather unpleasant photo. Aphids are gross, but golden mummies are one of the best things I ever learned about IPM.
We’ve had a couple of outbreaks of aphids this spring, first with the lupine when it put out a big flush of new growth and now on our kales as they begin to bolt. Golden mummies are the brownish, mummified carcasses of parasitized aphids; wasps lay their eggs in the aphids and the larva eat the aphids from the inside, leaving the dried husks. If you aren’t familiar with them, click on the photo and you should be able to see the difference. In the garden, another way to tell the difference is that aphids move and mummies don’t.
When you see an outbreak of aphids, the presence of golden mummies is one sign that natural predators are present. Count the aphids and golden mummies on a leaf, and, if the outbreak includes at least 10 percent golden mummies, the natural predators will deal with the outbreak for you. Spraying would kill the natural predators along with the aphids and therefore be counterproductive, though aiming a spray of water against the aphids to knock them off (which actually kills a large percentage of them, while not harming the beneficials) is okay if you want to speed the process.
In the photo, I count 14 golden mummies (mostly on the right, but three in the population of aphids on the left) and estimate about 100 aphids, so our IPM is working. Our earlier outbreak on the lupine was the same way, and it resolved itself without intervention.
This entry was posted on Wednesday, April 22nd, 2009 at 11:16 am and is filed under edibles, various critters. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.