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HomeGardeningLearn how to Establish and Management Carrot Weevils

Learn how to Establish and Management Carrot Weevils

Listronotus oregonensis

The very last thing you wish to discover when it’s time to drag your carrots is {that a} bunch of grubs beat you to the anticipated carrot crunching.

These candy, crisp roots have been speculated to feed you and your loved ones, not some small, hungry weevils!

What are you able to do?

A close up vertical image of a carrot weevil (Listronotus oregonensis) larvae in the soil. To the top and bottom of the frame is green and white printed text.

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It turns on the market are a number of methods to stop and management these undesirable snackers, to maintain them from decimating your hard-earned harvest.

All the pieces you want to find out about these weevils and methods to just do that’s laid out for you beneath!

Right here’s what we’ll cowl:

What Are Carrot Weevils?

These weevils are native to North America and although they are often pests almost in all places on the continent, they’re a selected downside within the jap United States and across the Nice Lakes in each the US and Canada.

As their title suggests, they love carrots, however can even assault different members of the Apiaceae household, together with celery, parsley, and parsnips.

A close up vertical image of a carrot weevil larvae infesting a crop.

The snout-nosed adults do nibble on the foliage, however their larvae are the true downside, attacking the roots with gusto.

The feeding tunnels they create are nice entry factors for pathogens.

However carrot rust flies additionally assault the orange roots, so how will you inform which pest you’re coping with?

Take a better have a look at the tunnels.

Carrot rust fly injury is principally targeted on the underside two-thirds of the basis and the feeding tunnels might be rust coloured.

Carrot weevils depart darkish tunnels, usually gaping open, and their injury is usually concentrated within the higher third of the basis.

After all, when you see the larvae of both sort inside, you may get out your hand lens and attempt to establish which pest is the issue. We’ll discuss that within the subsequent part.


The eggs this pest lays are white, slowly darkening as they mature and turning black simply earlier than they hatch.

The larvae are cream-colored grubs with no legs and a lightweight brown head capsule.

A close up horizontal image of an adult carrot weevil (Listronotus oregonensis) on a purple surface.
Grownup. Photograph by Whitney Cranshaw, Colorado State College, Bugwood.org.

In case you see larvae and want to establish whether or not you’ve a Psila rosae downside or a L. oregonensis downside, carrot rust fly larvae are stiff, white to yellow-brown coloured maggots.

The pupae, just like the larvae, are additionally cream coloured.

The adults are six millimeters lengthy, darkish brown-gray snout-nosed beetles.

Biology and Life Cycle

These pests disperse by strolling, not flying. (This is a vital truth for later).

Females chew a gap within the petiole or crown of the younger plant and lay two to 4 eggs inside, masking them with a darkish, sticky secretion. This mark is called the oviposition scar.

In a single to 2 weeks, the larvae hatch and chew tunnels down into the basis. Younger crops might wilt and die consequently.

After going by means of 4 instars, they pupate, after which emerge as adults. These pests can full one to 2 generations per yr.


Egg laying begins mid-Could to early June, when the crops are previous the four-leaf stage.

Diploma day fashions have been developed for this pest.

Once we discuss diploma days, we imply an accumulation of days above a sure temperature, on this case 45°F or 7°C. Egg laying begins at 147 diploma days, and a complete of 630 are wanted to finish one technology.

That is useful to know because it permits farmers to foretell when oviposition, for instance, is more likely to be taking place.

You may look ahead to oviposition scars on the foliage and crown of the plant, however at that time the injury has already been performed, and they’re tiny and really onerous to seek out.

A close up horizontal image of rows of carrots growing in the vegetable garden.

Traps are a extra standard and easy choice to see you probably have a weevil downside.

A selected sort referred to as Boivin traps are made by strapping collectively two foot-long items of wooden with grooved “tooth” on the sides for the weevils to cover in as they feed on the carrot bait within the hollowed out middle.

Test the lure each three to 4 days and exchange the carrot earlier than it begins rotting. On industrial farms, a mean of 1 and a half weevils per lure warrants intervention.

Natural Management Strategies

On this part you’ll discover quite a lot of management strategies you’ll be able to make use of as a part of a whole built-in pest administration (IPM) technique to try to regulate these unwelcome bugs.

Cultural and Bodily Management

Bodily management may imply hand-picking the offending bugs off the plant, or on this case, excluding them from the crop by masking the crops as quickly as they emerge – or earlier – with floating row covers.

A close up horizontal image of a floating row cover protecting crops from pests.

Cultural strategies usually allude to adjusting planting and rising circumstances and parameters to evade the pest and provides the crop the higher hand. Typically, these strategies benefit from the pest’s biology and lifecycle.

For instance, since overwintering is achieved close to the host crops and the adults are weak fliers, you should utilize crop rotation methods to keep away from planting in the identical spot as you probably did the earlier season.

This could show you how to to keep away from nearly all of the primary hatch.

Management alternate host weeds, comparable to hemlocks, wild carrots, and different Umbelliferae members of the family surrounding the backyard to scale back overwintering websites and take away further meals and oviposition websites.

A close up horizontal image of wild Daucus carota flowers growing in the garden.
Blooming wild carrot.

Reasonably than harvesting a carrot right here and there, harvest complete blocks or rows at a time. Filter any crop residue on the finish of the season as nicely.

If attainable, delay planting till after when many of the first-generation adults could have died, which may very well be in mid-June.

Organic Management

A number of species of parasitoid wasps will assault these weevil eggs, notably these within the Anaphes and Anagrus genera.

Although they’ve restricted effectiveness in massive scale industrial monoculture, in your smaller and extra numerous backyard, they may do some injury to the carrot weevil inhabitants.

Restrict foliar insecticide use and develop crops that present nectar and different meals sources to draw and feed the adults.

Some kinds of useful nematodes will assault these pests, particularly Steinernema carpocapsae and Heterorhabditis bacteriophora, that are out there at Arbico Organics in a combo pack.

A close up of the packaging of Arbico Organics NemAttack and NemaSeek Beneficial Nematodes isolated on a white background.

Helpful Nematodes

Apply these nematodes combined in water at or simply after planting to permit them to ascertain and work preventatively.

Natural Pesticides

Sadly, there aren’t any natural pesticides confirmed to be efficient towards these pests.

Beauveria bassiana merchandise might have an effect on a larva right here and there, however trials present that making use of a majority of these fungi-based merchandise has no impact on injury and outcomes general.

In case you want to apply a product to regulate these pests, chemical pesticides are your finest guess.

Chemical Pesticide Management

As a result of the larvae are safely hidden within the roots and the adults have restricted susceptibility to chemical substances, chemical pesticide decisions are restricted.

Some pesticides utilized by industrial farmers are malathion, diazinon, methomyl, and sure pyrethroids, however as acknowledged above, utilizing chemical substances shouldn’t be the silver bullet.

In your house backyard, chemical pesticides are additionally not the reply to each insect downside, usually killing extra of the great bugs than the unhealthy, resulting in a growth within the unhealthy insect populations that’s unchecked by predators.

Get That Snout Out of My Carrot Patch!

These long-nosed beetles are usually not the best pests to cope with, however you probably have an infestation, the number of cultural strategies described above can provide you a great leg up on them.

Plus, creating a great atmosphere for his or her predators and parasites by rising a various backyard – and one which’s chemical-free, if attainable – is crucial.

That’s, in order for you much less injury and extra of a harvest that appears like this:

A close up horizontal image of freshly harvested carrots set on a wooden surface.

Have you ever ever had points with these pesky weevils in your backyard? Tell us within the feedback beneath the way you seen and the way you handled them!

Whilst you’re at it, examine different carrot pests and extra on methods to develop these scrumptious crunchy root greens right here:


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