Tag Archives: IPM

Ew.

I know I know. Big-girl gardeners don’t say “ew.” But no matter how hard I try to appreciate and understand it in spite of its appearance, the earwig simply elicits an “ew” response from me.

Earwig
Earwig. Photo courtesy Andrew Dennes.

Up until recently I considered these to be a mostly benign insect, not particularly liking them but not feeling any particular malevolence for them. I can recognize also that they’re part of the delicate food web, playing roles as decomposers, detritovores, fungivores, etc. Earwigs are also a food source for birds, insectivorous mammals, amphibians, spiders, yellow-jacket wasps and even bats (http://en.wikipedia.org/wiki/Earwig). That I find the insect particularly unattractive should not lead to its demise.

Until I planted some mustard greens and noticed holes accumulating in the leaves daily. Initially, I wasn’t able to determine the culprit- no caterpillars or other little bugs and the holes just didn’t jive with my experience with slugs and snails which tend to munch much more wholeheartedly from the outside in. A bit of research and a little garden digging et voila – earwigs! In retrospect, I’ve deduced that this past year of attempting to plant seeds and see them sprout and then perish may be at least in part due to the work of earwigs (and their nymphs) in the garden. Earwigs also have been known to feed on clover, lettuce, cauliflower, strawberry, seedling beans and beets, grass shoots and roots, as wells as a variety of tree fruits. Scavengers indeed!

The reason for their inconspicuousness is that they hide during the day, feeding on plants only in the wee hours of the evening. As with all things, earwigs are not all bad. I found through my research that they prey on aphids and other insect eggs and can provide a fair amount of biological control. So it seems the ideal approach is to seek a middle ground- to find a way to reduce populations enough so that tender little plants can grow enough to be able to not be completely demolished by the little bugs but not make excessive attempts to rid the garden of earwigs entirely (an impossible feat anyway, especially for a chemical-free garden).

The solution I found (through UC Davis IPM website) is to sink a can or low-sided container into the ground filled with vegetable oil. They also suggest adding a drop of fish oil, but I don’t have any and yes indeed, it seems to be working pretty well without!  Though now our concern is that the little vats of oil filled with juicy bugs may be a veritable buffet for other little critters that may visit our garden. We’ve often joked about setting up an infra-red camera to witness the nocturnal life of our garden – or perhaps it is best just not to know.

Recovering mustard greens by can of vegetable oil.

In the above image, notice the old, damaged mustard greens among the healthier new growth. Perhaps soon we’ll be able to harvest the lovely greens…and I suppose figure out a way to prepare them – Any suggestions?