September 08, 2014
I got the following question through my web site. I'll answer it below. I was trying to wait until I had a good photo of these little critters, but I don't seem to have very many of them these days, so there's no photo for this post.
My veggie garden has been besieged by roly polies. When I check gardening blogs, most answer that roly polies do not eat live plant tissue but they are definitely eating the base of my cucumber and squash plants. I caught most of them early and taped the base of the stems so they couldn't continue to gnaw away...but they have!!! They continue to move up the stem even though the stem is tougher than when they were small seedlings. I have lost a few plants to them. My vegies are mulched with my homemade compost which is a cold one and probably supports the rolly pollies. How do I rid my soil of them? They are everywhere!! BTW I live in San Rafael, Marin County. Should I solarize the soil?
The answer:Too many garden how-to books and other guides are researched by reading what others have written, so we get the same information over and over. And wrong information over and over is frustrating.
Roly Polies will generally eat any living or dead plant matter that is soft enough, inlcuding much dead, decaying plant matter. If there are only a few of them, they may not damage crops much, but when their populations build up, they do significant damage. While I've never seen sow and pill bugs eat squash stems, I have watched them chew up the blossom ends of summer squash fruit and eat into ripe tomatoes.
"Roly Polies" is a general common name for both sow bugs and pill bugs, which often occur together in gardens. These are two different species of animal, both more closely related to shrimp than to insects. We call the species that can't roll up sow bugs, the ones that form a tight ball when disturbed, pill bugs, but their habits and management are about the same.
Your goal is to make conditions unpleasant for them and to reduce their numbers if they get so numerous that they are becoming pests. Start by pulling the mulch back from your squash plants, leaving a bare area a few inches wide around them. Try to keep this surface, especially, but all of your garden soil or mulch surface, as dry as possible, since these creatures need to stay moist to survive.
I doubt that solarizing the soil will help with sow and pill bugs. They would tend to run out of the hot area under the plastic. You might get eggs, but the adults are very mobile.
Sow and pill bugs tend to congregate in moist dark places in the day time. You have to move fast, but if you know where they are hiding, and see a lot of them in one place, you can scoop them into a plastic bag, seal it, freeze it, and compost them. Or you can leave out traps, in the form of anchored opaque plastic sheeting or cardboard, remove it fast, and start scooping. Try using a kitchen scoop or a deep trowel.
If you have many sow and pill bugs in an area you are about to clear and replant, try to reduce the population before you plant seeds or set out new seedlings there. Waiting a couple of weeks may be enough, but if you have many of the creatures, you may want to use mechanical means, as just described, or chemical means, as follows, to reduce the population.
I never use chemical means as a first resort, but you may want to supplement your cultural and mechanical methods by using a product called SluggoPlus. In addition to the iron phosphate that kills snails and slugs, it contains Spinosad, an extract from a soil microorganism, that is toxic to sow and pill bugs, earwigs, and cutworms. Use it according to directions, including not spreading it any more thickly than the directions indicate, as it is toxic to pets. (If spread according to directions, very thinly, it is less likely that a dog might eat enough of it to harm it, but do read the directions.)
Good luck reducing your roly poly problem!
Another tip is that if you are watering too often, keeping plants wet most of the time, you will encourage roly-polys. If you are having an overpopulation, try not to wet the plants when you water. If they are fairly well-established, try to water them well, then wait a few days to a week, so the surface soil can dry out, making it less appealing to the roly polys. A soaker hose is a good investment, since it can be put in place and left on long enough to soak the soil deeply. Hand-held hoses, after the plants are established, tend to encourage short watering periods that don't soak very deeply (because the person holding the hose gets bored), so you end up watering too often and keeping the surface too wet.
Posted by: Pam Peirce | May 09, 2021 at 10:34 AM
thank you! This helps tremendously. Perhaps we can save the rest of the new annual flowers we just put out. They're eating down the row.
Posted by: Ranae Guiles | May 02, 2021 at 11:51 AM