What Are Pickleworms: Tips For Treating Pickleworms In Gardens

By: Kristi Waterworth

They may sound like the residents of your favorite fictitious childhood world, but pickleworms are serious business. In this article, we’ll walk you through identifying pickleworm damage and tell what you can do about these nasty little caterpillars.

Moths appear in a huge variety of shapes and colors, often visiting nighttime barbeques or flitting through the garden after dark. Unlike so many other insects, moths are helpful pollinators that never cause garden damage, right? Unfortunately, some moths are the parents of unruly offspring like the pickleworm. These obnoxious pests are serious trouble when it comes to cucurbit plants.

What are Pickleworms?

Pickleworms are the larval stage of the pickleworm moth (Diaphania nitidalis) and much like the caterpillars of beautiful butterflies, this stage of development can be extremely damaging to gardens. Pickleworms are aggressive eaters, preferring the buds and fruits of cucurbits, especially winter and summer squash, cucumbers, gerkin and cantaloupe.

Early infestations can be difficult to detect, but if you look closely, you may notice perfectly round holes chewed into vine ends, blossoms or fruit with soft frass coming out through tiny holes.

Pickleworm damage can be serious, especially if the worms have already spread through your garden. Those tiny holes they’ve chewed in your blossoms are likely to prevent fertilization, so fruits will be few and far between. Any fruits that do make it, but are bored into later, are likely to be riddled with bacterial and fungal colonies that invaded after the pickleworm started working its way through.

Pickleworm Control

Treating pickleworms is no easy feat either. Once you’ve got an active infestation, it’s easier to salvage what you can in the garden and prevent future outbreaks. Start by asking yourself, “What do pickleworms eat?’ and carefully check each and every cucurbit plant in your garden. Any fruits with holes or frass should be immediately destroyed to prevent the spread of secondary infections. If you catch them early enough in the season, tearing your plants out and starting again may be the easiest course of action.

Next season, protect your plants by covering them with floating row covers at night (uncover them during the day so bees can pollinate their flowers). Since pickleworm moths are active after dark, nighttime protection is the best prevention.

People who live in areas where pickleworms cause problems year round may want to spray their cucurbits with Bacillus thuringiensis proactively as the plants grow. Once the caterpillars are inside the plant tissues, it’s too late for treatment, so spray early and spray often.

This article was last updated on

Read more about Cucumbers

Melon Pests

Summer is in full swing and the melon patch seems to be growing nightly! Cantaloupes and watermelons have set fruit. With enough water these babies will grow quickly to maturity. However, water isn't the only limiting factor to your melons producing bountifully this year. While cucumber beetles and flea beetles may have been attacking your young melon seedlings, now that the vines have grown, other pests are a greater concern. Be on the lookout for these pests in your melon patch.

Spider mites are very tiny, spider-like pests that attack a variety of plants such as melons. Most gardeners don't notice them until they see the webs spider mites form. Heavy feeding by spider mites causes stippling ? tiny holes ? in the leaves. If severe, their feeding can cause leaves to die. When their population is small, they and their damage are hardly noticeable. However, during periods of hot, dry, dusty summer weather, spider mite populations can explode.

To control spider mites, spray leaves with forceful jet of water from a hose to dislodge them.You can also try spraying insecticidal soap, hot pepper wax, or horticultural oil on the leaves.

Aphids are small insects that feed on melon leaves. They tend to attack once the melon vines starting running. Aphids are small sucking insects that come in colors ranging from light yellow to black. Heavy feeding can cause leaf dieback and reduction in melon quantity and quality. They also can spread diseases such as cucumber mosaic virus.

Like spider mites, aphid populations explode during periods of hot, dry weather. Encourage natural predators such as lady bugs by planting flowers around the melon patch and having a water source such as a water garden nearby. To control severe infestations, spray the undersides of the leaves with insecticidal soap or hot pepper wax, and place yellow colored pans filled with water in the melon patch to catch adults. The adult aphids are attracted to the color yellow.

Although their feeding is most severe on squashes and pumpkins, squash bugs do attack melons and can cause considerable damage to leaves. These flat-backed, brown bugs emerge in spring. They lay clusters of red-brown eggs on the underside of leaves which hatch into small brown nymphs that look similar to the adults. The young and adults feed on the leaves.

Squash bugs like to hide you usually won't see them until you turn over an infested leaf. They will scurry away under other leaves and plant debris. You can use this secretive nature to trap them. Placing a piece of cardboard under the plants, check under it every few days, and crush any squash bugs congregated there. Control the adults early in the season to reduce problems when the population explodes in late summer. Control heavy infestations of nymphs with applications of neem oil. Clean up the site well in fall to remove places where adults can overwinter.

Although pickleworms will attack watermelons, most of their damage is seen on cantaloupes and other melons. The yellowish-white larvae feed on melon flowers, buds, and fruit. You probably won't notice them until you harvest and open the fruits. Pickleworm adults migrate to northern gardens from warmer regions and lay eggs on leaves in early summer. They hatch and feed on blossoms and developing fruit.

To control pickleworms, plant early maturing melon varieties such as 'Dallas' that you can harvest before the pickleworm population swells. Destroy rolled up melon leaves since they may contain pickleworm pupae inside.

For more on growing and caring for melons and watermelons, go to the Virtual Vegetable Guides at www.willhiteseed.com/store/asp/guides.asp

Caterpillars on Tomatoes

Q. I found several large caterpillars munching on my tomatoes . What should I do to get rid of them?

A. It sounds like you're seeing tomato hornworms, which can grow to an alarming size (5 inches long)! Like most larvae in the butterfly and moth family, hornworms can be controlled by spraying Bt, (Bacillus thuringiensis). This organic control only affects only the larvae of butterflies and moths, not beneficial insects, animals, or pets. However, since Bt can take a few days to start working and tomato hornworms can do a lot of damage in a short time, just remove the ones you see by hand. Pick them off and place the hornworms in a pail of soapy water.

If you see a caterpillar with what looks like grains of white rice all over it, relocate it elsewhere in the garden rather than killing it. It has been parasitized by a braconid wasp and what you're seeing are the eggs. These small wasps are harmless to humans, but will help keep the hornworm population in check.

Charlie Nardozzi is an award winning, nationally recognized garden writer, speaker, radio, and television personality. He has worked for more than 30 years bringing expert gardening information to home gardeners through radio, television, talks, tours, on-line, and the printed page. Charlie delights in making gardening information simple, easy, fun and accessible to everyone. He's the author of 6 books, has three radio shows in New England and a TV show. He leads Garden Tours around the world and consults with organizations and companies about gardening programs. See more about him at Gardening With Charlie.

Coffee to Compost

Hmmm, what is this gooey clearish gunk on my cucumbers? It seems to be coming out of this little hole…

There’s a worm on my cucumber!!

It can be a bit disconcerting to decide to enjoy one of your fresh cucumbers and discover that a caterpillar beat you to it.

The first sign that you have a pickleworm problem is the clearish frass (technical term for poop).

There are some ways to deal with these freeloaders, though.

1. Super Organic: Eat the cucumber, worms and all. Embrace your inner insectivorous self.

2. Mildly Organic: Wash the cucumber and cut off the wormy part. If you harvest your cucumbers little and often, they will not have gotten very far into the cuke. Slice it up and serve in a Fresh Cucumber Tomato Salad with Basil.

To prevent the moths from laying eggs on them again, you can cover them with netting at night (when the moths are actively laying eggs) and remove it early morning so the bees can pollinate the crop

Alternatively, my Michelle from Pensacola Permaculture said that she had good results from rubbing off the faded flower once the cuke had been pollinated.

3. Organic: Spray with neem oil. For more organic ideas, including this one, click here.

4. Not Very Organic: Spray plants with Drano. Unfortunately, this method renders the cucumber unfit for human consumption, kills the host plant, and it is not recommended that you even attempt to grow anything in that spot ever again.

5. Fit of Rage Revenge: Drench cucumbers in liquid radioactive waste. Not for amateurs. Very effective against those caterpillars, but seldom used due to going-to-jail concerns. Don’t garden in that block ever again, even if you don’t go to jail or die from the radiation yourself.

How do you deal with pickleworms in your cucumbers?

Personally, I just cut off the affected part and eat the rest. Apparently they migrate, and so if your plants survive through the infestation, you should get more once they move north.

I’ve had my fair share of them this year, and have still had enough to make some amazing refrigerator dill pickles!

Vegetable Garden Pests: Beware the Pickleworm!

Just inside from harvesting vegetables, I heard yelling from the kitchen. She was staring at a freshly washed cucumber in the sink. Sprouting from it were green projections that were alive and wriggling! This was our introduction to the insect pest with the unique name of pickleworm.

These critters are the larvae of the pickleworm moth (Diaphania nitidalis), which overwinters in Florida and becomes a late summer pest of cucurbits (not only cucumbers, but summer and winter squash, pumpkins, cantaloupe, and watermelons) in Western North Carolina.

Once the moths arrive in our area, they lay eggs on cucurbits, which hatch, go through several larval stages, pupate in the plants’ leaves or in the leaf litter, and become adults in less than a month! This short life cycle means we may see two or even three generations of pickleworms a year.

The larvae can feed on flowers, leaves, and vines, as well as fruits. Larvae eating blooms can prevent fruit set. Like squash borers (Melittia cucurbitae), in the worst-case scenario, pickleworm larvae feeding on the vines can kill your plants. You may see pickleworm excrement (frass), or simply small holes in your fruits. In both cases, your crop is ruined once the larvae are feeding because the damaged areas with start to rot. According to University of Florida’s John L. Capinera, cantaloupes, with their thick skins, may have external damage called “rindworm.”

Pickleworm Larvae and Damage to Squash

  • Early planting. Plantings that mature before the moths arrive are likely to escape pickleworm damage.
  • Resistant varieties. Some squash varieties that are more resistant: summer squashes Early Prolific Straightneck, Early Yellow Summer Crookneck, and Summer Crookneck and Butternut 23 winter squash.
  • Floating row covers. Using row covers at night can prevent the night-flying moths from egg-laying, while still allowing pollinators to visit the flowers by day.
  • Garden clean-up. Removing damaged fruits and vines can prevent further generations in the same gardening season.

Pickleworm, University of Tennessee Publication # W206:

University of Florida Featured Creatures:

Insect Management on Cucurbit Vegetables in North Carolina

How to Prevent European Corn Borer

Regular cleaning and proper maintenance are some of the best preventive measures against the European corn borer. Make sure that the environment is clean, and hence, it will not be attractive to pests. After the growing season, it is also advisable to destroy the stalks and throw them away. It serves as a site for overwintering, so it is a good idea to discard them so that the pest will not be able to find a suitable breeding ground. As much as possible, you should also concentrate planting varieties that can resist European corn borer.

For those in Alabama, the Farming Basics Mobile App is a great tool for looking up insect pest information and connecting with regional Extension agents. Also, subscribing to the Alabama IPM Communicator Newsletter can help you stay informed about training events, crop production, and pest alerts.

This research and educational program is funded by grants from the Alabama Department of Agriculture and Industries Specialty Crops Block Grant, USDA SARE, OREI and Beginning Farmer Programs.


Previous Article

What is late blight and how to deal with it

Next Article

Top dressing of onions: mineral and organic fertilizers for onions