How to Keep Asparagus Beetles From Ruining Your Crop

Views: 3546

Spring is the time of year when every new vegetable is precious and delicious. Asparagus is one of those that is particularly yummy, and many gardeners can’t wait until it’s time to pick this early season delicacy. But even this vegetable is subject to infestations of the asparagus beetle.

Common and Spotted Asparagus Beetle

Not surprisingly, the two pests that attack asparagus are the common and spotted asparagus beetles. Both are very small—only about ¼ of an inch long— but the common has a darker body with a half dozen cream colored spots on its back.

The spotted asparagus beetle is bright orange with a dozen dark spots. Some people think it looks like a lady beetle, but it’s far more elongated and has a very different head.

Basically, what both of them do, although the common asparagus beetle usually does more extensive damage, is chew and lay eggs on the spears, plus they devour the foliage of the asparagus ferns.

The common beetle hits the asparagus shortly after it emerges in the spring, while the spotted beetle comes out a little later in the season.

If your asparagus is curling over at the top, kind of like a shepherd’s crook, there’s a good chance it’s asparagus beetles. They also leave scarring, and sometimes you can see the dark brown eggs along the asparagus spears. They make a mess of things, and ruin a lot of asparagus if there are too many of them.

Prevent Beetle Damage

One way to keep them in check is to cut those spears every day. This way you’ll eliminate any of the eggs, and enjoy a delicious side dish for dinner.

You want to cut the spears back to just below the soil level. And to really gain control over the situation, remove the asparagus berries once they appear. It only takes 7 to 10 days for the eggs to hatch. The interesting part of their life cycle is the larvae crawl up to the asparagus berries and burrow inside. They consume the seeds inside the berries until they’re mature—typically a couple of weeks. Then they’ll spin a thread and drop to the ground. Afterwards, they burrow just underneath the soil and pupate. There can be several generations each season.

This gives you another opportunity to take them out. If you use a hand cultivator to scratch around the asparagus, you’ll most likely kill a fair number that might be just below the soil line.

You’ll also want to clear the debris away from your asparagus to minimize the places for them to hide because once they emerge, they’re going to be hungry and they’ll head right for your plants. And be vigilant about checking the ferns later in the summer. They feed on them, as well, and can seriously weaken the plant if they defoliate them too much. You can hand-pick them in the afternoon when they’re the most active.

The bad news about asparagus beetles is they are very common just about everywhere. The good news is there are non-toxic ways to deal with them so you’re not losing this delightful spring vegetable.

(The asparagus pic is copyright Tramont-ana from istock)

Meet Amy Grisak

Amy is a freelance author and photographer in Great Falls, MT who specializes in gardening, foods, and sustainable agriculture. She provides information on every kind…

Amy's Recent Posts

Leave hollow stems for native bees.
Hollow Stems for Native Bees: Leave the Garden a Little Messy
Read this post
It's important to know the allelopathic qualities of some garden plants, such as broccoli.
How to Know the Allelopathic Plants in Your Garden
Read this post

Amy's Videos

How to Safely Rid Your Indoor Plants of Pests
By Amy Grisak
Watch this video
Treating Fruit Trees for Fire Blight
Treating Fruit Trees for Fire Blight
By Amy Grisak
Watch this video

Membership Has Its Perks

Become a registered user and get access to exclusive benefits like...
  • Ask The Expert Questions
  • Newsletter Archive
  • PlantersPlace Magazine
  • Members Photo Gallery
  • Product Ratings & Reviews
  • Garden Club Samples

Here’s more information about gardening that you’re going to want