Wireworms and Their Control Wireworms collected from potato traps, ready for the chickens. What are Wireworms?Wireworms are the larval form of click beetles (Elateridae family) and look like a thinner version of a mealworm. It is their slender size that gives them the common name of “wireworm.” Click beetles are typically black or brown and are recognized by the distinctive “click” sound they produce when they flip over from a position on their backs. Adult click beetles are herbivores, but they rarely cause issues with feeding. Wireworms, however, live in the soil and can cause agricultural damage. Some species can persist in the soil for up to 6 years until they transform into adult beetles. Wireworms are red-orange-brown in color with a hard, shell-like coat. Some wireworm species feed on seeds, cotyledons, seedlings, roots, and the underground stem portion of a plant, and can cause harm or even kill plants, particularly small seedlings. They also bore into and eat potatoes, garlic, beets, carrots, and other root vegetables, making them unpalatable, reducing storage time, and/or causing them to rot. How do You Know you have a Wireworm Problem I began to notice that my young brassica plants would occasionally wilt and die suddenly. When I pulled up the plants, there were almost always one or more wireworms feeding on the roots. Eventually, I started noticing I had garlic plants that were yellow and stunted. Again, when I pulled them up, there were usually wireworms feeding on the bulbs. Wireworms can also cause decreased seed germination if they feed on the seeds before they can emerge. If you till your garden, you can also keep an eye out for wireworms. We only till once or twice a year, but our ducks have learned to recognize the sound of the tiller, and they follow behind it, gobbling up all the bugs they can find. Another option to determine if you have wireworms is to set traps, generally made with a chunk of potato or a handful of seeds. I use the potato traps and will describe them in more detail below. Wireworm PreventionAdult click beetles like to lay eggs in the soil of weedy or grassy areas in fields and gardens. Once hatched, the larvae burrow further into the soil to feed on seeds, roots, and other organic matter. If you have recently turned over sod to make a garden area, you will likely have a higher number of wireworms. If possible, let the soil rest for a year before planting. Eliminate as many grassy and weedy areas in your garden as possible to reduce the number of eggs laid by these pests. Since our garden is part of our fenced-in orchard and vineyard, we have lots of grass for the click beetles to propagate, which may partially explain why we have a wireworm problem. Also, make sure your soil drains well, as wireworms thrive in damp soil (at least in Wisconsin). In other areas that receive less rain, different species are adapted to drier soil. However, my biggest problems with wireworms occur in my raised beds, which, for the most part, drain very well. Last summer, 2024, we received massive amounts of rain, which may explain why I have been trapping so many wireworms this year, even after having trapped hundreds of them last year. Update: once again in 2025 we received above average rainfall in the spring and early summer and once again I trapped hundreds of wireworms. Another way to reduce wireworm damage to seeds is to not plant too early. Many people, especially in our short growing season in zone 4 Wisconsin, including myself, often plant as soon as the daytime and nighttime temperatures warm up. However, for seed germination, it is the soil temperature that matters. If the soil is too cold, seeds take longer to germinate and get established, which gives the wireworms more time to find and eat the seeds.  Wireworm potato traps (orange flags) in a raised bed. Wireworm ControlMost plants are less susceptible to wireworm damage once they are larger and out of the seedling stage, so it is best to start wireworm control early in the spring. The exception to this is root crops, which are susceptible throughout the growing season. So, if you do have a wireworm problem, what are your options to control them? Commercial farms sometimes use insecticide drenches to treat the soil. If you do this, you must treat early, before planting. Even though I use pesticides sparingly, when needed (to treat invasive buckthorn and prevent fungal diseases on my fruit trees and grapes), soaking my soil with insecticide before planting is not something I am comfortable with. My go-to method is to use potato traps. I cut potatoes into about 2-inch chunks and then place a wooden skewer (like those used for grilling) into the potato with flagging tape tied around the top of the skewer. I bury these potatoes about 2-4 inches deep into each of my raised beds (~6/bed). Every few days to a week, I check the traps and remove any wireworms that have burrowed into the potato (then I feed them to my chickens). This method is very effective in trapping wireworms, but it is also very labor-intensive since I have so many raised beds (18 right now). I do not even bother trying to put traps into my in-ground garden, as this would increase my labor significantly. Ideally, traps should be placed before you plant. I did not place traps last fall or early enough this spring, and I have already lost many garlic plants to wireworms this year. Interestingly, the wireworms much prefer my “Chesnok Red” garlic over my more robust “Music” garlic, so I will probably only grow “Music” from now on. Another option to control wireworms is to use beneficial nematodes, which kill the wireworm larvae. Nematodes are microscopic roundworms that evolved naturally to kill various insects. Specific species of nematodes have been selected to target specific agricultural insect pests. The advantage of this method is that once they are applied, the nematodes continue to work throughout the growing season and over time, can dramatically reduce the wireworm load in your garden. The disadvantage for me is that they are relatively expensive. Since I have a huge area that I would ideally treat (my fenced-in garden area, including the orchard and vineyard, is 40,000 square feet) it would cost me roughly $700. If I treat only my raised beds, this is much more affordable at approximately $50, but this leaves many wireworms outside the treated area, including my in-ground garden, which will turn into adults that can move around and lay more eggs. I have treated just my raised beds in the past, which may or may not have been effective (likely due to lack of rain and not enough watering). Another disadvantage of nematodes is that you have to water the area to be treated before you apply them, you then apply the nematodes with water, and then you water the area again, after you apply them. Ideally, the area should stay moist for a couple of weeks after you apply them to help the nematodes burrow into the soil more easily. One year, when we tried nematodes, we had a drought year and probably did not keep the area moist enough for them to be effective (watering the garden that year also wore out our well pump, which ended up getting replaced that summer). The last disadvantage for those in northern climates is that the nematodes do not overwinter well, so ideally, you would treat every spring for optimal control. Even with all of these limitations, I am a huge fan of beneficial nematodes IF you have a small garden and can keep it well-watered until they are established. Nematodes are an organic, natural control option for those unwilling to use more traditional chemical methods of control. Although this method is labor-intensive to start, it continues to work all summer long, which will likely save time compared to potato traps. Other ideas that can help reduce wireworm pressure include tilling the soil in the fall (and again in the spring) to expose wireworms to predators such as wild birds (or in our case, domesticated ducks). You can also try crop rotation, such as not planting root crops in the same garden bed each year or leaving a garden bed fallow for a year (while still keeping it weeded).  Wireworms burrowed into a potato trap, ready to collect. References and Resources
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AuthorIn 2016, my family and I moved from the New York City area to small town Wisconsin. Our move, this website and blog (and our previous Etsy store) is the result of our desire over the past several years to simplify our lives, increase our quality of life, reconnect with nature, and enjoy a more self-sufficient life. I grew up as a country kid in central Pennsylvania working on my grandfather's fruit farm and as a corn "de-tassler" at a local seed farm. My background is in biology where my love of nature originated. I am a former research scientist and professor and have now transitioned to a part-time stay-at-home mom, self-employed tutor, and small business owner. Thank you for taking the time to check out my site. Archives
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