Black Blister Beetle Battles

Another unforeseen issue has arisen in my garden: blister beetles!  These voracious beetles are systematically devouring the foliage of our plants.  So far they’ve taken turns tasting our tomatoes, tomatillos, and even a clematis.  I’m not heartbroken over the clematis as it’s a sweet autumn clematis that grows like a weed – it will come back.  But I do want the tomato plants in the vegetable garden to prosper and so I need to find a way to eliminate the blister beetles before the foliage is all removed.

Black Blister Beetle Eating a Tomato Plant

I have what are called black blister beetles.  Blister beetle larvae are predatory insects that love to eat grasshopper eggs but when the larvae mature they become vegetarian and only eat the leaves of your favorite plants…

Black Blister Beetle on Tomato Plant
Black Blister Beetle with droppings

I noticed our blister beetles when I saw some strange droppings on top of the leaves and on some tomatoes in the vegetable garden.  Droppings are usually a sign of some sort of infestation – and usually aren’t good although there are some possible exceptions like the larvae of butterflies like monarchs, swallowtails or other garden beauties. I looked above the droppings and found the black beetles on top of my tomatoes munching away.

I immediately went for the neem oil.  Neem oil is an organic extract from the neem tree that is useful in deterring pests and plant diseases.  The beetles didn’t like the neem oil and I thought I had found the trick but they just moved on to the next tomato plant, but they didn’t return to the first one.  Then I adjusted my strategy and mixed up soapy water in a sprayer.  That annoyed the beetles, they scattered around, and moved on again but didn’t leave as I had hoped. I guess the tomato plant next door is just as good as the one I sprayed.  My next strategy was mixing a wormwood (artemisia) and catnip tea into the soapy water.  Again I was merely an annoyance.

My next course of action will be diatomaceous earth which I’ve read on various forums should do the trick.  Another recommendation I’ve seen in several places is to mix lime and flour together.  I’ll go the diatomaceous earth route first then update you on the results!

Have you ever had blister beetle sin your garden?  How did you deal with them?

2 thoughts on “Black Blister Beetle Battles”

    1. I continued to use the soapy spray through the season with some neem oil on occasion, It either did the trick or they left of their own accord but I have not had them in my garden since 2012.

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