Worm Control On Parsley: Information On Deterring Parsley Worms

Worm Control On Parsley: Information On Deterring Parsley Worms

By: Amy Grant

If you happened to notice worms on your parsley, dill, or an occasional carrot, chances are they are parsley worms. Read on to learn how to manage worms on parsley.

What are Parsley Worms?

Striking caterpillars, parsley worms turn into even more striking black swallowtail butterflies. They are easily identifiable as green worms with a brilliant, yellow dotted black band across each body segment. When the caterpillar is disturbed, it protrudes a pair of fleshy “horns,” the better to scare predators away. This larval stage of the gorgeous black swallowtail can grow up to 2 inches long.

Parsley Worm Life Cycle

Female black swallowtail butterflies are slightly larger than males and as is usual in nature a bit duller in color than their male counterparts. The wingspan may be up to 76 mm (3 in.). Both are velvety black in color with tailed hind wings marked with peacock-like eyes. The females lay spherical, 1 mm (0.03 in.) across eggs that change in color from pale yellow to reddish brown. Four to nine days later, the eggs hatch and young larvae (instars) emerge and begin feeding.

The yellowish-green parsley worm is the butterfly’s larval stage and its body is transverse with black bands and yellow or orange spots. The “horns” mentioned above are actually scent organs. The young larvae look similar but may have spines. The pupa or chrysalis appears dull gray and mottled with black and brown and is around 32 mm (1.25 in.). long. These pupae overwinter attached to stems or fallen leaves and emerge as butterflies in April-May.

How to Control Parsley Worms

Worm control on parsley is fairly simple, if you really desire their eradication. They are easy to spot and hand pick. They are also naturally attacked by parasites, or if you must, insecticides such as Sevin or Bacillus thuringiensis will kill off the caterpillars.

Although parsley worms are voracious eaters, the benefit of attracting a future pollinator (and a stunning one at that) may outweigh worm control practices on parsley. Me, I would just plant a few more parsley, dill or whatever the insects are feeding on. Healthy plants will usually recover from the foliage loss and parsley worms will not sting or bite humans.

Deterring parsley worms is a bit more difficult. If you find the caterpillars truly objectionable, you might try row covers. Covering your tender crops may aid in deterring parsley worms.

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Parsley Worm and The Butterfly it Becomes

This is a story about the parsley worms in my backyard. My garden is small, and a bit unique in that at the present time my vegetables are in pots and fabric bags. I use fresh parsley often, and I have it growing in two locations.

One day I found this colorful worm crawling along a parsley stem and munching away. I could see that he had chewed off many of the surrounding leaves. This striped guy is appropriately called a “parsley worm”.

I couldn’t remember what type of butterfly it would become, (had to look that up) but I knew it was getting ready to form a chrysalis.

Turns out it’s a Swallowtail butterfly that emerged from the green chrysalis a few weeks later. The wrapped worm was attached to a stem of basil, which had gone to seed, but was in the same pot as the parsley the worm was eating.

But here’s what happened first. I found the worm sitting in this position (below) and he was no longer eating. In fact he was on the basil now, and not the parsley. This is where he formed his chrysalis. I checked it every day, and after a few weeks, there was something new to see.

Worm beginning to form a chrysalis

Once the butterfly “hatched” he crawled to the top of the basil stem to try out his new wings. Maybe this is the perfect set up for encouraging butterfly production. I hope it happens again.

Arrow pointing to the empty chrysalis

A few days ago I happened to go outside and saw this beautiful black butterfly at the top of the basil stem, and I knew… the baby was born! The wind was blowing, but he held on for hours. I kept checking on it, and then suddenly he was no longer there.

I felt like a proud parent. I had helped a new baby butterfly enter the world. Course, I had done nothing but plant the parsley… haha. But I felt good. And I’m glad I was able to see the beautiful butterfly before it flew away. I took lots of photos, like a proud parent does, and one video.

Perennial Herbs

While most vegetable gardens are annual affairs, tilled and replanted each year, it is worthwhile to find some space that can remain undisturbed from year to year to give crops the benefit of pest-repelling perennial herbs. Rosemary, a shrubby perennial in warm climates, repels cabbage moths, bean beetles and carrot flies when planted with those crops. Chives deter aphids, mites and Japanese beetles, as well as rabbits -- a larger garden pest. Sage repels the same insects as rosemary, as well as flea beetles, which prey on potatoes and sweet potatoes. Garlic, a perennial herb, deters Japanese beetles. All varieties of mint are effective against cabbage moths, flea beetles, aphids and even mice, though mints need to be grown in pots because of their invasive habit. Consider edging your entire vegetable garden with a planting of attractive wormwood (Artemesia). Its white foliage discourages slugs as well as small foraging animals.

Growing Parsley

Just about everyone has seen parsley used to garnish food. Sometimes people forget that it is good to eat too. Very good in fact and also super healthy being rich in nutrients like Vitamin C.

Varieties of parsley

Parsley is from the Apiaceae family. . . same as carrots, and originates from southern Europe around the Mediterranean.

Home gardeners usually prefer curly parsley (Petroselinum crispum). It is mild flavored and grows to roughly 30cm with flower and seed stalks reaching to 80-90cm (35").

Be patient, a warm soil temperature will help. Once your seeds have germinated, you'll be happy to see your little plants romp away and produce for a long time.

In rows, thin the plants so that they stand approximately 25cm (10") apart. If growing window-sill or glasshouse pots, crowding them in a bit more if often done. in fact 2-3 plants in one pot will work if you're constantly snipping the outside sprigs off.

A Few More Parsley Care Tips

Like most herbs, the more you pick them, the more they produce, and in parsley's case, the sweeter it tastes.

Many people sow new plants each year, or you can just let one of your plants go to seed and either collect the dried seed heads, then sow later, or let nature scatter the seeds willy-nilly in your garden.

Cutting off the emerging flower stalk in parsley's second season, will give you quite a few parsley sprigs to eat, but you won't be able to ultimately stop a plant dying. As it starts to kick the bucket, pick what you can, but the leaves will become slightly bitter and the stalks rather chewy!

Although parsley is best used fresh, it can be frozen. Just put small bunches in bags or containers and keep them in the freezer until you need them.

They won't be crisp or bright green when they thaw, but they can still add color and flavor to dishes.

Problems and Pests of Parsley

Luckily parsley is a breeze to grow and resists most pests and problems, but just occasionally you could get unlucky.

  • Aphids, Whitefly and Spidermites
    These pesky pests usually attack other plants, but if found on your parsley, bursts of water from a hose will often dislodge them quick smart. Read more on these pests and other ways to control them on natural pest control.
  • Other pests
    Like gardening the world over, some plants and pests thrive in one area but not somewhere else. So parsley grown in your friend's garden up the country might collapse, whereas you never have a problem.

But if you do notice damage, quickly try and identify the culprit, be it certain weevils, worms, blight and so on, and apply the solution.

Parsley is near about the best herb in the world. just because it is. I bet most people would agree with me. How on earth would we cope without parsley to sprinkle on scrambled eggs, garnish a soup, pretty up a plate of sammies, and raise the flavor of just about anything?

List of Herbs — Check out more herbs to grow.


The parsleyworm is quite spectacular as caterpillars go. It is colorful and it is big. It is a 2 inch caterpillar that is green with bright yellow-dotted black band across each body segment. It gives off an odor and projects orange horns when it is upset.

It is the larvae of the black swallowtail butterfly, another beautiful creature. They are black with yellow spotws on the edges of their wings, a taillike projection on the hind wings, and a 3 inch wingspan. They are found all over the United States.

Growth Stages
The adult butterfly lays white eggs on the leaves of the parsley plant or on some relative to parsley such as celery. The eggs hatch and turn into pupa which winters over in debris of some kind. Several generations occur each year.

Parsleyworm will eat the foliage and stems of plants in the parsley family including carrots, celery, dill, and parsnips. Chunks of leaves taken from along their edges are typical signs of parsleyworm attack. Often only stems remain. In a very short period of time, parsleyworm can defoliate a small plant.

How Many Make a Problem? - Just because you see one caterpillar, do not panic. A few Parsleyworm cause little damage and are food for the birds. Also those Parsleyworms turn into what we consider to be the pretty black swallowtail butterflies that many of us want in our yards. What you look for is the damage. When you can notice that almost 1/4 of the plant is damaged, then some action is definitely necessary.

Bob Lollo©
Parsleyworm In Action

Stress Encourages Pest Problems
As we note in most of our pest insect files, most insect problems, including caterpillar problems occur after a plant has become stressed for some reason. Healthy plants can usually handle a few Parsleyworm wandering around chomping here and there. A plant that is in stress however, seems to have an alarm system sounding that attracts lots of Parsleyworm at one time. So if one of your plants is attacked by a bunch of Parsleyworm, deal with the insect problems, and then spend a few moments trying to figure out if maybe there is something you can do to relieve the stress problem.

Do you have a gardening question? Ask Nancy

Good planning is key to a successful vegetable garden

Whether you are new to growing your own food or have been growing a vegetable garden for years, you will benefit from some planning each year. You will find everything you need to organize and plan your vegetable garden in my PDF eBook, Grow a Good Life Guide to Planning Your Vegetable Garden.

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Natasha Garcia-Lopez is an avoid home-gardener and proud owner of 88 acres of land in rural West Virginia. She was a member of the Association for Living History Farms and Agricultural Museums for many years and is currently enrolled in the Oregon State University Master Gardner Short Course program so she can better assist you with your gardening questions.She holds a certificate in natural skincare from the School of Natural Skincare.

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