Asparagus Beetles, Part 2 —Tips to Prevent an Infestation

Photo credit: U of M Extension Service

I recently discovered asparagus beetles in my garden…and a great website from the University of Minnesota Extension that shares what you can do about them.

If you do find these unmistakable spotted buggers in your home garden, you can hand-pick them. Since I’m an old hand at bug-picking, I had no problem with hand-to-hand asparagus beetle combat. 

(More in my April newsletter, the Little Farm Horror Movie, including my free mini-ebook about tent caterpillars.)

Keep in mind, however, that capturing the beetles is not a one-and-done operation. Like with tent caterpillars, you may need to pick the beetles all through the insects’ life cycle. 

For asparagus beetles, that could be the length of the growing season.

The U of M Extension people recommended tossing the beetles into soapy water, but I’m allergic to almost all soaps and detergents. So as soon as I went outside, I poured a small amount of apple cider vinegar into an empty yogurt container, added an equal amount of water.

Prepared for the long haul—i.e., all summer—I clambered over the rabbit fencing into the asparagus patch started in.

There were a LOT of beetles. Although they’re small, I wondered how could I have missed them before. And worse, these beetles can fly!

Which complicates your capture; you’d reach for a beetle and off they’d go. It reminded me of days of yore, when wily caterpillars would wiggle away just as you tried to grab them, and they’d fall into the grass where you couldn’t see them.

But on the plus side, these beetles aren’t in the least bit squishy, so a win.

The website said to pick in the afternoon, while the bugs are most active. So I spent about 20 minutes picking in the middle of the day, make another turn around the patch in the early evening, then one last pick shortly before sunset.

I probably got 30 or 40 bugs that first picking, and put a lid on the container before I quit for the night. The next day, upon fetching my container, I discovered the beetles were still swimming!

Okay. These guys were tough. Stronger measures were required. I got another container, poured in a measure of full strength white vinegar, and went at them.

Asparagus beetles chewing on my veggies!

With all the stalks they’d damaged, many shriveled and inedible, I found a strange satisfaction in picking these bugs. I felt even better when I got a two-fer: grabbing two beetles as a time when they’re engaged in…um, making beetle babies.

So for four days, I picked three times a day. Then the next four days, I picked twice a day. I think by now I’ve caught a couple hundred of them.

And you know what? It works! After my intensive picking, I've been finding only one or two in the patch, then after that, nothing!

However, I’m keeping in mind that I might have just picked the first generation of beetles, and their life cycle could be starting all over again. But here’s the beauty of keeping an organic garden:

Helpful pests!

I’m not crazy about all the ants we have everywhere--in the garden, in the  yard, and in the woods. But when I found lots of beetles on an asparagus stalk, I also would find loads of ants busily working over the stalk too! My guess is, the ants were feasting on the beetle eggs.

With the beetles gone (for now, and fingers crossed for the rest of the summer), the spears look healthy and robust again. New tips are pushing out of the soil every day, just as they should. Because of the earlier damage, I’ve only harvested about half or even a third of the number of spears I normally would. I want to make sure the crowns keep their vigor.

Healthy spears again!

So the asparagus patch will be thick with ferns this summer. It’ll be more difficult to weed, that that’s a trade-off I can live with!

I’ll keep inspecting the beds—as I indicated above, I wouldn’t put it past these beetles to create at least one or more generations over the summer. I didn’t exactly need yet one more garden job, but there you are.

I did learn one more crucial beetle management tip: Maintain your asparagus bed in the off season.

Over the winter, you must clear all the dead foliage and other debris. Leaving it in the bed provides shelter for overwintering pupa.

So as it turns out, my bad. This past winter, the foliage stayed vigorous, right up until the first of a series of severe Northeasters here in the Foothills. So I didn’t clear the asparagus bed until March.

Still, after all this bug-picking this summer, you can bet the entire area will be clean as a whistle next winter!

If you enjoyed this post, you can find more about homestead-style gardening and “homesteady” living in my monthly Susan Colleen Browne newsletter—it's free and open to all, so there's no need to subscribe to read it…

The latest issue: "Homestead Diary & A Tale of Two Irish Movies." I hope you’ll take a look!

~Susan