A reader wrote to us to ask what kind of worms eat potatoes underground. Worms are evidently borrowing into our reader’s potatoes (or “potatos,” if you simply can’t tolerate the randomness of English spelling), leaving close to nothing behind. Not surprisingly, the reader was also wondering how to get rid of these potato worms. Of course, in order to get rid of a worm you need to know what it is, so we’ll begin by answering our reader’s first question: we suspect he found wireworms (sometimes incorrectly spelled “wire worms”), which may or may not be attacking the potatoes in conjunction with another creature. Without any pictures or a physical description of the creature our reader found, it hard to be sure that he did in fact find wireworms, but wireworms definitely seem to be the most likely candidate. In most discussions involving worms and potatoes, wireworms come up.
It should be noted up front that wireworms are actually not worms at all. Rather, like so many other so-called “worms,” they are larvae; more precisely, they are the larvae of click beetles. The term “click beetles” is very broad, ranging as it does over nearly 10,000 distinct species of beetles. Taxonomically speaking, click beetles make up the family Elateridae. All click beetles (as well as a few other types of beetles) have a clicking mechanism that allows them to essentially spring into the air, enabling them to, say, avoid predators.
Since there are so many different click beetle species, it stands to reason (indeed, it is biologically necessary) that there are many different types of wireworms. Among other things, this means that not all wireworms are agricultural pests. Some wireworms are predators of other insect larvae, for instance, while others – in fact, most – survive on decaying or dead organic matter (and so wouldn’t eat living agricultural products).
The wireworms that do feed on a living vegetables and fruits can be enormously problematic for gardening or farming operations. Wireworms have a slow development process that can often take three to four years, and during this time they simply stay below the soil and feast on organic matter. Sometimes they merely consume the roots of wild plants, but often they make their way into agricultural settings and eat several types of crops, particularly potatoes it seems, but also crops like strawberries and wheat. What’s more, they are very good at finding food because they can track carbon dioxide gradients that plants produce in soil. And finally, they are not easily killed by insecticides, as they will often recover (sometimes after months) even after exposure.
So, what is our reader to do? Unfortunately, since the wireworms have already afflicted our reader’s patch of potatoes, there doesn’t seem to be much he can do to salvage his present round of potatoes. What he can do is take measures before he plants his next crop of potatoes. The reader should make sure to turn the soil over a few times in an effort to pick out any wireworms he may find. He could also set up potato traps (i.e., buried potatoes that attract wireworms) before he plants in an effort to preemptively collect the wireworms that might otherwise attack his soon-to-be planted potatoes. Finally, he should plant a type of potato that can be harvested earlier in the growing season, as wireworms tend not to attack until about mid-August.
We can’t be certain, but we are reasonably confident that our reader found wireworms. One issue we mentioned, but didn’t get into any details about, is that it is possible that more than one creature is attacking our reader’s potatoes. For example, slugs often attack potatoes, sometimes utilizing the tunnels that wireworms have already borrowed through potatoes (although they work alone too). So, even assuming our reader definitely found wireworms, we regretfully must add that this might not be all he found.
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