Earwigs are a creepy nuisance at times, like when they crawl out of freshly picked flowers or lettuce heads, but they are not a pest. They actually clean up fungal infections on plants.
A typical earwig. Credit: animal.discovery.com
For several years in this town, I found that one could not grow a hollyhock to bloom without it becoming covered with an ugly rust by the time it bloomed. I would cut them down when they got ugly and let them re-grow to bloom later in the summer, when the rust is not so prevalent.
But one year, I didn’t see any rust on my hollyhocks, and so didn’t cut them down. As they were blooming, I was lying on the lawn one day, looking up at them, and noticed that the leaves were full of tiny holes in the same pattern as the rust would make, and so was a butterfly bush. That evening, I noticed earwigs climbing the butterfly bush as it got dark, and put two and two together; the earwigs were eating the rust before it made spores and became colorful.
I had previously noticed that I had a great many earwigs in my gardens and thought about various strategies for getting rid of them, though I noticed no damage that I could attribute to them. Now I realized that they were actually useful, and stopped worrying about them.
In Landscape Management at RCC, our teacher pointed out that plant diseases like rust make typical damage patterns that differ from those caused by plant-eating pests. After several years of observing such damage, I was able to see the difference right away between pest damage and fungal damage cleaned up by earwigs. Since then, I have noticed earwig work on other plants with other fungi.
Earwigs are just one of the many beneficial insects that are encouraged by leaf mulch. Many predators of plant pests live under mulch and rocks, along with pests that they may or may not eat, like snails, slugs, grubs, and grasshoppers.
A variety of soldier beetle common in Southern Oregon. Their color patterns vary widely.
Soldier beetles eat aphids in April and May and then lay their eggs in mulch-covered soil. Their velvety black larvae crawl under the mulch for the rest of the year, eating a great many insect eggs and baby bugs. You will rarely if ever see the larvae; they are exceedingly shy. It’s hard to even find photos of them.
A ground beetle typical to Southern Oregon. Some are iridescent; some have big heads.
Ground beetles, spiders and centipedes also hunt beneath the mulch. Leaves aren’t the only mulch they like, but they are probably the best, apart from a tendency to be eaten up by worms, pill bugs, millipedes and earwigs. Coarse bark mulch can keep the soil covered when the soft leaves are eaten up. Keep your soil predators happy with good mulch, and you will have few pest problems.
Rycke Brown, Natural Gardener 541-955-9040 firstname.lastname@example.org