So, you have asparagus beetles eating your next harvest.
And you need to stop them. Fast.
In this article, we’ll cover:
- Why you have asparagus beetles
- How to identify these beetles
- Natural ways to get rid of them
- How to control, manage, and repel them
- Tips and tricks designed to stop them from coming back
- And more
Sound good? Let’s get your asparagus growing straight, not hooked.
Last updated: 7/2/20.
What’s an asparagus beetle?
There are two main types of asparagus beetles.
As their name states, their favorite plant to munch on are the spears of asparagus vegetables.
Are you growing asparagus? Are you noticing eggs, wilted, twisted, or damaged foliage?
Then you probably have some degree of these brightly-colored beetles (who have no agenda other than to eat up your harvest!) eating up your plant!
The asparagus beetle has a few different aliases.
Since there are two main types, multiple names have been made up:
- Common asparagus beetle
- Spotted asparagus beetle
- Orange spotted beetle
- Spotted orange beetle
- Blue or black asparagus beetle
- “Tiny black things” on asparagus
- Shiny asparagus beetle
Types of asparagus beetles
There are two types that are commonly found in the US.
The first type is the common asparagus beetle, which is believed to have European origins.
This particular beetle eats both wild plants found in nature and garden plants
The other type is the spotted asparagus beetle. This one looks very similar to a ladybug, with the spotted pattern on the back wing covers.
The spotted beetles are the lesser of the two evils, as they’re not as destructive to asparagus plants. They mainly feed on just the plant seeds rather than the actual fruiting portion.
But the common asparagus beetle needs to be controlled quickly as they’re the baddest of the bunch. This beetle is what you commonly see on the tips of the asparagus. Asparagus damage can be seen and the vegetable may grow to “hooked” or “twisted” rather than straight.
Adults and larvae will be different in appearance.
The adult beetles are the pest you’ll come across all over your asparagus. But the larvae are just as destructive and have a completely different physical appearance compared to the adults.
Don’t get confused- both the larvae and the adults are the same pest.
But the larvae look like tiny slugs whereas the adults look like a beetle.
Asparagus beetles have a distinct appearance with their striking colors and warning patterns.
They vary in color and size depending on the species and local environmental conditions. Favorable environments lead to larger beetles, whereas highly competitive ones lead to smaller ones.
The spotted asparagus beetle has exactly 12 black spots on its hard shell with an orange to reddish coloration. They’re known to be a destructive pest and the most common type of asparagus beetle you’ll encounter.
The common asparagus beetle is about 0.25” in length and has a metallic blue tinge that can be silver to black. They have yellow spots and reddish highlights on their wing covers.
They have bordered elytra with a noticeable pattern on their covers.
Their color is lustrous and will shine under sunlight.
The larvae of both of the two types of beetles look like miniature slugs.
You can differentiate them because the spotted asparagus beetle larvae are completely orange, while the common asparagus beetle has visible limbs with a silver or green coloration.
They also have a black head rather than the orange color. This is an easy technique to tell the difference between the common beetle and the spotted beetle.
You can find out the exact type of beetle problem you’re dealing with on your edible plants.
Asparagus beetles have a similar life cycle similar to any other beetle.
Both species will overwinter and hide in sheltered leaf litter or plant matter.
They also hide in the trash and waste bins, compost bins, and other organic matter. Since they overwinter, the cold season doesn’t kill them.
The adults mate and then deposit their eggs in precise rows of 3 to 8 on the spears of asparagus plants. The eggs appear dark brown in color and are visible to the naked eye. You’re able to scrape the eggs off if needed.
After a week or so, the larvae will hatch and start to feed immediately. The asparagus will grow along with the larvae and this slowly moves the larvae up the plant.
As they feed, they’ll continue to grow and develop a voracious appetite for the plant. This continues for a few weeks.
Following the extreme feeding from the larvae, this can result in damaged asparagus spears. If you have a large number of larvae, the asparagus will appear withered or worn with visible plant damage.
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The larvae will pupate after a few weeks. They drop to the soil and will complete pupation within a week. The adults then emerge from their metamorphosis and climb up the asparagus stalk to feed again.
Most beetles will produce two life cycles. The number of larvae and adults eating up your plant can inflict heavy damage and kill your harvest.
Depending on the beetle species, some may start or end their life cycle later. The spotted beetle hatches later than the common beetle.
Spotted beetles only deposit a single egg that’s completely green. The larvae will eat the asparagus berries for two weeks and then drop into the soil to pupate. The adults will then emerge about two weeks later.
Spotted beetles end their breeding season in July.
Are asparagus beetles harmful?
Many gardeners who grow asparagus have some number of beetles and don’t mind them.
These beetles are hard to completely eliminate from the plant, and small numbers of them rarely will cause any damage that’s significant other than a few lost harvests.
Seeing a few here and there should be no reason for alarm. But if you come across dozens of eggs just waiting to watch on your spears, then you should act quickly.
Asparagus common beetles only feed on asparagus as their sole host plant.
Both the larvae and the adults eat the needles of the fronds, which reduces the ability to photosynthesize. The spears will also get chewed up and covered with eggs which reduce the marketability of the plant.
This also depends on the type of beetle you’re dealing with.
Spotted asparagus beetles are less of a problem compared to the common asparagus beetle. If you see a common beetle, you should take action.
But if you see a spotted one, you have less to worry about.
These spotted ones only eat the berries of the plant and aren’t considered to be nearly as harmful as the common beetle.
Orange spotted beetles only feed on the berries of the plant, so they’re not as harmful to the plant as the common asparagus beetle.
How to identify asparagus beetles
Their bright orange marking makes them stand out and easy to spot, even on their host plant.
They’re definitely not the masters of camouflage. The orange-spotted beetle is readily seen and can be noted as eating the leaves of mature asparagus plants. The larvae will eat the spear tip.
The common asparagus beetle is blue or black with a metallic luster, yet should be on the only beetle-like pest on asparagus heads.
When you see eggs deposited in neat rows on the tip of the plant, this is a sure sign you have common beetles. The eggs may also be found on the flower of your asparagus plant.
If you see a green egg (usually by itself), this is a sign of orange-spotted beetles.
Can you eat asparagus beetle eggs?
You should wipe off the eggs before cooking and consuming them. If you can’t remove all the eggs, throw it out.
The eggs don’t hurt the plant, but after they hatch, the larvae become a problem. As for human consumption, you need to remove all the eggs before using the edible portions.
When are asparagus beetles active?
You’ll see these beetles come out during the warmer months. They come out during the spring and summer. These are a diurnal (daytime) species, so it’s easy to spot them during the daytime.
The orange spotted species is even easier to see as their coalition stands out on the green spears.
Similar to any other beetle, they prefer hotter temperatures and emerge when the asparagus spears are visible. This is usually between April and May.
They come out when the spears of your asparagus grow out.
Does the cold kill them?
Asparagus beetles aren’t killed by the winter temperatures because they hide in plant shelter. They overwinter and will stay hidden until spring when the temperatures pick up again.
Signs of asparagus beetles
There are some easy techniques to tell if you have asparagus beetle infestations on your edibles.
The most common symptom is the twisting of the asparagus head, which results in your spear becoming “hooked” and curving backward in a U-shape. This is also known as Shepherd’s crook.
You’ll also notice visible damage to your plant as the larvae munch nonstop on the plant. There will be scars on your plants with damaged portions that are easily seen.
Beetle poop (frass) may also be visible on the asparagus.
Other signs of beetles on your asparagus:
- Spear tips turning a dark brown
- Wilted asparagus tips
- Damaged or weakened spears
- Visible larvae or adult beetles
- Diseased plants from a weakened state
- Less viscous spears
- Fewer asparagus harvested
- Brown eggs on the stem of an asparagus flower
How to get rid of asparagus beetles naturally
Asparagus beetles can be difficult to get rid of because of their sheer numbers.
Therefore, you’ll need to see which home remedy works best for your specific beetle problem.
If you don’t have a TON of beetles on your veggies, then simple DIY organic control methods (like manually picking them off) can work.
But if you have a lot of beetles crawling all over your asparagus, you’ll want to resort to a more extreme approach.
Regardless, try these out and see if they help get rid of the pests. You just may be able to save yourself some cash for small infestations.
Remove them by hand
While it may not be the most pleasant way to pull these beetles off your plants, you can use a variety of manual methods to eliminate them.
Obviously, this only works for small beetle infestations.
Simply removing them will diminish their numbers rapidly and if you repeat the process daily, you’ll be making significant reductions in overall beetle populations.
Use soapy water
Get a bucket of soap water (a few drops of dish detergent and a liter of water).
Put on some garden gloves and wear some long sleeves. Then go out and manually remove them by hand.
Drop them into the bucket of soapy water. It’ll kill them after a few minutes. Do this daily when the beetles are out and about.
Use a handheld vacuum
You can use a vacuum to suck them off if you don’t want to squish them each time.
This makes it a lot faster, but you do have to empty out the bag or canister each time you suck them off your plants.
This is because they can still crawl out of the vacuum reservoir and reinfest different plants.
Remove any visible eggs
While you’re removing them manually, you’ll also want to check for the presence of beetle eggs on your asparagus plants.
This is effective because you’re basically removing dozens of beetles at once and preventing the future generations from hatching. The beetle eggs look like tiny silver to brown eggs that are deposited on the spears of your asparagus.
Use a magnifying glass for a closer look.
Check each time you remove the beetles because the adults may lay eggs overnight and you’ll see a bunch of them the next day.
You can scrape off the eggs using a garden spade or razer and toss them into a container with soapy water to kill them.
They shouldn’t hatch regardless once they’re off the asparagus, but it doesn’t hurt to be safe.
Use a hose and spray them off
A hose can be an effective tool to easily remove the beetles from your plants.
Just turn the nozzle setting to “jet” or “stream” if you have an adjustable nozzle (or just do the old cover-up-the-outlet-with-your-thumb trick) and blast off the bugs.
The stream will remove them quite easily.
Repeat this whenever you’re outside watering your plants. A hose is a fast, easy way to minimize their numbers without having to touch them.
Use a brush to remove beetle larvae
The last manual method is to use a plant brush.
Of course, you can use anything really (BBQ brush, sink scrubber, toilet brush, sponge, etc.)
Use the brush and brush your asparagus plant to quickly remove the beetles. You should position a container filled with soap water below so they’ll fall into it and drown to kill them quickly. This works against adult and nymph beetles.
You can also soak the brush into the solution to purge any beetles stuck on it.
A brush or garden hose is especially useful against getting rid of beetle larvae.
Once the larvae drop off the plant (because of you or an external force), they usually can’t climb back onto the asparagus to continue and feed. This can help save, protect, and diminish their numbers to reduce the damage to your plant
Lure natural predators to eat them
There are plenty of bugs and animals that’d be happy to eat up your beetle problem.
Depending on where and what native species you have in your area, you may be able to use them to eat up the asparagus beetles.
There are a lot of different types of predators that eat beetles:
- Predatory wasps
- Other inverts and mammals
There’s enough information online for you to get a full list of beetle-eating predators.
Here’s a decent resource for you to check out.
See what’s native to your area and do some research to see how to attract more of them.
Because of the vast variety of different beetle enemies, there’s no way to compile them all into this article! But you’re sure to find at least a few that are native to your backyard.
Raise chickens for natural pest control
Chickens are one of the best natural foragers of all time.
Most states allow you to raise chickens in your yard, but you should double-check with your state and local ordinance to see the regulations.
Chicken is a common hobby of many enthusiasts and there are plenty of online forums you can read to see how to raise them prosperity.
Hint: Raising chickens is easy and they practically raise themselves.
Plus, you’ll get some organic eggs for yourself as a treat (along with fewer pests in your garden).
Chickens will automatically forage and eat beetles (among other pests) by themselves all day when the sun is out. Then they come back to their nest to roost at night.
They’ll do this for you, every single day, for free.
You should consider getting a pair of chickens just for the natural “janitorial” cleanup they can provide your yard. They’ll scavenge, forage, and pick off beetles all day off of your asparagus.
Chickens will also eat worms, grubs, maggots, caterpillars, aphids, ants, larvae, flies, bug eggs, and the list goes on and on.
Chickens also won’t’ damage your asparagus, and they’ll keep your yard’s pest population in check.
And don’t forget the free-range natural eggs you’ll harvest.
What more could you ask for?
Attract birds to eat the beetles
Similar to chickens, you can attract birds to your garden to help clean up the beetles.
They’ll naturally forage and seek out small insects to eat.
There are a lot of different species that eat beetles:
- Eastern kingbirds
- Purple martins
- Blue jays
- Old World sparrows
Check out which birds are native to your property and see how you can attract more of them.
Unlike chickens, birds rarely have any regulation to the number of birds you can bring into your yard. So you can use chickens or birds (or both) to work for you to eliminate the beetles on your asparagus.
Basic things like bird feeders, birdbaths, birdhouses, perches, and other things can help make your yard more bird-friendly. I’m not a bird expert, but you can check out this resource for additional tips.
Harvest asparagus early
As you probably know, the beetles are there because they want to eat up your asparagus plant.
If you harvest on time, rather than waiting until it’s overripe, this will help minimize pests from eating it.
Asparagus beetles continually feed on your plant-based on a regulated beetle life cycle that matches up exactly with the asparagus growth.
The larvae, nymphs, and adults all attack different parts of the vegetable depending on the time of year.
In simpler terms, the larvae and nymphs will eat the asparagus spears. The adults will eat the same thing, but prefer asparagus with some hefty leaves also.
This allows them to have additional feeding sources and lets them breed and deposit eggs as it shows the plant is mature enough to handle another generation of beetles.
The surefire way to break the beetle cycle is to just harvest early for one season.
All of the infested asparagus should be pruned and harvested before ripe to discourage the beetles.
This will break the natural lifecycle they’ve built around the asparagus plant in your yard and may force them to leave- as conditions have become unfavorable.
But then again, beetles are extremely adaptable and may change their lifecycle to match the early harvest. So be wary of this.
The early harvested asparagus can still be eaten. Just make sure that you rinse off beetles and eggs and cook to the right temperature to kill any remaining ones. If it looks beyond edible, toss it out.
Continue to harvest your plant spears before they’re ripe. This may take a few seasons to work and you need to continually monitor for beetle activity.
Are there fewer beetles each time your harvest? Or does it not change?
Harvesting early will also prevent other pests from showing up as many eat up ripe or overripe plants, like fig beetles.
Keep your garden clean
Have a messy, unkempt yard?
Remember that asparagus beetles overwinter in the soil and other plant matter.
If you keep your yard clean and free of debris, you minimize the shelter provided for them to continue their lifecycle. Cleaning up your garden also stops other bugs from establishing a nest or colony in your yard.
This is basic practice, but often overlooked by many homeowners but is extremely effective to prevent pest problems for good (permanently).
Here are some actions to consider:
- Remove all leaf litter
- Keep the lawn mowed
- Prune your plants
- Get rid of clutter
- Remove plant foliage
- Check water features
- Keep water drains clear
- Secure trash and waste areas
Overfeterlizeing your plants may actually bring more beetles to your yard (and other insects).
This is because the spears tend to grow faster with abundant plant food. Larger spears mean larger beetle colonies can be supported.
Similar to overfertilizing, overwatering is also just as bad.
Excess water in the soil makes it easier to burrow for the larvae to pupate and the adult beetles to overwinter. Moisture also attracts bugs to the plant.
Mulch and turnover your soil
During the winter months, the adult beetles will hide in the soil to overwinter.
If you mulch your soil or otherwise disrupt it during this time, you can force the conditions to be unfavorable for them and could mess up their overwintering process.
Unfavorable conditions are what keeps beetles out permanently.
Apply bacillus thuringiensis (Bt) on your veggies
Bacillus thuriniensis is a bacterial microbe that can help kill beetles by forcing pores within the beetle’s hard shell.
It’s commonly used in various pesticides globally and can be effective for killing a variety of bugs found in the garden. This bacterium is also used on farms and large-scale crop industries, so it’s a proven method.
Bacillus thuringiensis is a Gram-positive bacteria that lives in the soil and also naturally occurs in the wild.
You can purchase Bt from online retailers. Follow the directions on the packaging for proper application.
With proper usage, Bt can be a quick, affordable, and effective way to control and eradicate beetles on your asparagus.
Does neem oil kill asparagus beetles?
Neem oil can be used as a beetle spray and repellent.
You can buy neem oil in small bottles online. Make sure it’s pure neem and opt for the organic formulas only- especially because you’ll be applying it to a vegetable plant.
Follow the directions on the package and use as directed.
Neem can be a very effective beetle killer when used at the first sign of beetle detection.
Typically, it’ll be diluted in water and made into a spray, which you’ll spray on your asparagus.
Note that some people and pets may be sensitive to neem, and plants can be harmed if too much is sprayed. You should only spray it after the sun has set to prevent plant burning.
After you spray your plant, wash off any excess with a garden hose. Then let it sit on the plant overnight. Neem is sticky and forms a barrier over the plant which repels many different types of bugs- beetles included.
Although neem is organic by nature, you should still wash your edibles thoroughly before cooking and eating.
Neem oil is harvested from a tree and used to block pests from feeding on your plants because of the thin barrier it creates.
Use commercial pesticides
For those who plan to use commercial, store-bought pest killers, look for products that have pyrethrin as an active ingredient.
This is effective against beetle anatomy and used for the majority of bug killers.
Always get something natural or organic because if you’re spraying it on asparagus, you definitely don’t want to consume it. In fact, you should probably only use it to get rid of the bugs for this season.
After this, set up beetle repellents and wait until your next harvest to actually consume the veggies.
You can also use carbonates, spinetoram, and spinosad. Do your research and read reviews. These active ingredients are known for their ability to kill hard-shelled pests, amongst others.
You can also use botanical insecticides to spot treat specific spears. There are a ton of different brands available out there, but this is generally safer than using straight up poisons.
This will kill and eliminate the adults from continually feeding off of those plants, which will prevent future beetle infestations.
Consult a professional pest exterminator
When you’re out of ideas or you don’t know what you’re doing, contact a local pest control company. Most will do free evaluations and give you a quote.
Read some reviews online, reach out to a few companies, and get a few quotes. Some companies have annual plans to keep your home and garden free of pests.
So if your beetle infestation is out of control, they can keep coming back to treat the problem.
Here are some handy references you may find useful:
- Asparagus beetles in home gardens – UMN Extension
- Common asparagus beetle – Wikipedia
Did you get rid of the beetles on your asparagus?
Well, that’s all the tips I have for you.
You should have some knowledge about how to control, manage, and eliminate beetles from eating up your asparagus.
Be patient and use different DIY home remedies to see what works for you. Use multiple ones at the same time for a higher success rate.
Don’t be afraid to drop a comment if you have any questions below.
Or if you found this article helpful (or can be improved), let me know also.
Thanks for reading.
Currently an active researcher in the pest control industry for the past 8 years- with a focus on using natural and organic methods to eliminate pest problems.
I share handy DIY pest techniques I come across here to help out others (and possibly save them from a mental breakdown).
Fight nature with nature.