I’ve gotten many questions regarding the crazy amounts of moths that people are seeing right now.  Questions such as:

Why are they here?

Are they doing damage?

Is this a sign of things to come this summer?

Well, to begin, these moths belong to a group of moths called “Miller” moths.  This a generic name given to a bunch of mottled brown moths, but out west it commonly refers to the adult stage of the army cutworm.  In normal winters South Dakota and surrounding states experience cold enough temperatures that many of the adults are killed before spring.  However, with such a mild winter, many of the adults were able to survive and are now in the process of moving westward towards the Rocky Mountains.

The adult army cutworm doesn’t cause any damage and is more of a nuissance than anything.  They are attracked to porch lights so trying to reduce the amount of external lighting around your home should reduce this problem.  But, they can cause more serious problems for drivers where populations get too large…

Do these adult populations mean problems for the summer?  To be honest, it’s too hard to tell…  I’m not particularly concerned with their presence this early in the season.  The larvae are what we worry about and as long as we get moisture in the spring or fall, they will get drowned out and won’t be much to worry about again.

But before I end this post… 

Quick Question!  Does anyone know the best natural predator of the army cutworm?




Answer!  Grizzly bears!  Once the army cutworms migrate to the Rockies for the summer (they don’t like the heat and head to the mountains for the cooler temperatures and plentiful flowers to feed on) the grizzly bears also migrate further into the mountains to feed upon the cutworms.  I watched a documentary that mentioned that individual grizzly bears will feed on over 10,000 moths before the cutworms migrate back east!  Think of these moths as little energy packed vitamins…  The documentary also showed grizzly bears fighting over areas that had more moths than others.

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About jonathanixon

I am a dedicated and enthusiastic entomologist focusing on the expansion of public knowledge of entomology, proper IPM practices, and raising the awareness of beneficial insects within the home, garden, and crop systems. Insects are an infinitely diverse population throughout the world and are commonly misunderstood creatures. It is the goal of this blog to help share and promote their uniqueness throughout our internet community.

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