Caterpillars in the Garden

Caterpillars that you find in the garden are the larval stage of members of the order Lepidoptera (butterflies or moths).  Below, you will find out about six different caterpillars, learn how to spot them, and what to do about them.  The first one we will discuss is the tomato hornworm.

 

Tomato Hornworm (Manduca quinquemaculata)

a green tomato hornworm.
Tomato Hornworm in the caterpillar larvae stage

The tomato hornworm (from the order Lepidorptera) is found throughout the United States.  This five-spotted hawkmoth is a brown and gray moth with orange spots on its body and has a 4 to 5-inch wingspan and is part of the Sphingidae family.  In caterpillar larvae stage they are big fat green caterpillars that can be up to 5 inches long.

This stage is when they do most of the damage to plants.  You will find these caterpillars feeding on leaves and fruits of tomatoes, peppers, eggplants and potatoes.  If you see leaves with large holes and severe defoliation, devoured flowers, and/or scarring on fruit surfaces, you have tomato hornworms.

After overwintering in the soil in 2-inch reddish-brown spindle-shaped pupa’s the adult hornworm, commonly referred to as five-spotted hawkmoth emerges in late spring to early summer to lay their eggs.  They lay greenish-yellow eggs on the undersides of leaves.

Caterpillars feed for about a month then enter the soil to pupate (undergo a complete metamorphosis from caterpillar to moth).

There is usually one generation per year in the North and two or more in the south depending on the climate.

Controlling Tomato Hornworms

Tomato hornworm hawk moth. yellowish-greeen spotted with wide wing span.
Tomato Hornworm Hawk Moth
  1. Handpicking is the best way if you have the time and patience.  The caterpillars are not dangerous and do not sting.  You can drop them in a bucket of soapy water or feed them to your chickens.
  2. Also, you can use the organic pesticide Bt. (Bacillus thurigiensis) which acts as a stomach poison on some insects but does not harm plants or animals.
  3. If you use an insecticide you should first check with your local Cooperative Extension for a list of approved insecticides in your area.
  4. Prevent tomato hornworms by tilling soil at the beginning and the end of each season to kill the larvae overwintering in the soil.
  5. Wasps are a beneficial insect that feeds on tomato hornworms.  They attach themselves to the back of the hornworm, creating what looks like a grain of rice.  The hornworm will then soon succumb to the parasitic wasp.
Some plants that may keep tomato hornworms away from your tomatoes include:
  • Dill
  • Basil
  • Marigolds

These plants are also excellent companion plants and keep many pests away.

 

Codling Moth (Cydia pomonella)

Codling Moth in apple core
Codling Moth feeding on an apple core.

The codling moth is a member of the Lepidopteran family Tortricidae and is found everywhere apples are grown and is one of the major pests of this crop.  This is because the larvae are not able to feed on leaves, they are dependent on the fruits as a food source and can have a significant impact on agricultural crops.

What other crops will Codling Moths Attack?

Codling moths also attack pears, crabapples, apricots, and quinces as well as walnuts and stone fruits.

Caterpillars bore small holes in the fruit, usually at or near the blossom end.  Once inside the pinkish-white worm with a brown head feeds on the flesh leaving a sawdust-like frass (dropping).  Infested fruits often drop prematurely off trees.

Codling moth larvae overwinter in cocoons under loose bark on the tree or under debris on the ground.  In midspring they pupate, emerging in late spring as grayish brown moths.  The females lay an average of 50 to 60 eggs on leaves, twigs, and fruits.  The larvae feed briefly on the leaves before tunneling into the fruits.  After feeding for 3 to 5 weeks, they emerge and crawl down the trunk in search of a spot to pupate.

Depending on the climate, you may see up to three generations per year.

Controlling Codling Moths

  1. You can scrape loose bark in early spring to remove overwintering cocoons.  Then spray with a horticultural oil to eradicate eggs and first-generation early instar stages.  You can also band tree trunk with corrugated cardboard strips to provide a site for larvae to spin their cocoons.  Remove and destroy the strips after cocoons have formed.
  2. Also, you can use a microscopic, worm-like parasite, the beneficial nematodes.  They actively hunt, penetrate and destroy immature stages of this pest.  Spray trunks and branches as well as the soil around the tree to kill the pre-pupae larvae.
  3. In severe infestations you can use plant-derived insecticides.  Use when 75% of petals have fallen, followed by three sprays at 1 to 2 week intervals.
  4. Natural pesticides have fewer harmful side affects than synthetic chemicals and break down more quickly in the environment.

Cabbageworm (Pieris rapae)

cabbageworm, a bright green worm with a white line down side. It has short fuzz. Hanging on a branch.
Cabbageworm

The cabbage worm is found throughout the United States.  This group of insects is from the family Pieridae, type genus Pieris (garden whites).  It is the larva of a common white butterfly with three to four black spots on its wings.  In its caterpillar or larvae stage it has fine, short fuzz and is bright green.

The damage done by these caterpillars is similar-to the cabbage looper-the pests chew large ragged holes in the leaves of cabbages, broccoli, brussels sprouts, cauliflower, collards, kale, mustard greens, turnip greens, radishes, rutabagas, and kohlrabi.  Also, they bore into the heads, leaving trails of dark green frass (droppings).

Common white butterfly with black spots. Sitting on a purple flower stem.
Common White Butterfly

There can be several generations per year.

Cabbage Looper (Trichoplusia ni)

Green worm with a white or yellow strip down its side. Sitting on a head of cauliflower.
Cabbage Looper

The cabbage looper can be found in every region of North America.  The caterpillar is smooth and green with white or yellowish stripes.  It got its name because it arches its body as it crawls, like an inch worm.  It makes this looping motion because it does not have any legs in the middle of its body.

The larvae of a brownish-gray nocturnal moth, the looper is very destructive to plants due to its voracious consumption of leaves.  They chew ragged holes in the leaves, leaving a dark green frass (droppings) on the leaves of cabbage, broccoli, brussels sprouts, and cauliflower, as well as tomato, cucumber, and potatoes.  Later in the season they bore into the developing heads of these plants.

The caterpillar lays tiny yellowish-green eggs on the undersides of leaves.  Hardly noticeable to the naked eye.  It is usually not the caterpillar you notice first but the damage it causes.

You may see several generations of these per year.

Controlling Cabbage Loopers

There are several natural remedies and methods you can use to safely and effectively remove cabbage worms from your garden.

Here are some plants that are known to deter cabbage loopers and they include:

  • Allium
  • Borage
  • Garlic
  • Nasturtium
  • Onions
  • Rosemary
  • Sage
  • Tansy
  • Thyme
  • Tomatoes

Control Methods

  1. Plant these flowering plants and herbs near the plants you want to protect from the caterpillars in the garden.  Because they will attract natural predators, such as spiders, ground beetles, yellowjackets, and wasps, as well as sparrows, skylark, and goldfinch skylark.
  2. Crop rotation is another way to naturally reduce future pest populations.  Every few years plant a different type of crop in each section of your garden.
  3. To prevent the caterpillar from overwintering remove old and dead plant debris as quickly as possible.
  4. Tilling the soil between plantings help destroy the eggs and pupa.
  5. You can hand-pick them off, but it tends to be a losing battle if you have an infestation of any kind.  Put them in a bucket of soapy water to kill them.
  6. Also, you can cover your plants with a light-weight nylon so the butterflies cannot lay their eggs on the plant’s leaves.  But you will want to be sure to do this before you see any signs of the pest because your net could prevent natural predators from eating the worms.
  7. Sprinkling dry cornmeal or flour on damp leaves will kill the worms.  After they eat it, they bloat and die.
  8. You may want to try using diatomacius earth (also known as D.E. diatomite, or klesilgur/kieselguhr is naturally occurring, soft siliceous sedimentary rock, easily crumbled, consisting of fossilized remains of diatoms, a type of hard-shelled protist.  It is sometimes used as a filtration aid in soil.  Because of its abrasive and absorbing properties, it sucks the insects body fluid causing it to dehydrate and die. Wear a protective face mask and gloves when using this product.  You do not want to breath in any of the dust into your lungs.  It can be very dangerous!
  9. The natural insecticide BT, or Bacillus thuringiensis is very popular with growers.  BT is a natural soil-born bacterium that has been used as a natural insecticide for over 50 years.  It has been proven very safe to humans and the environment.

Homemade repellant

You could also make your own spray repellant by combining in a blender any combination  of the following ingredients:

  1. Garlic
  2. Mint
  3. Onion
  4. Hot peppers
  5. Horseradish
  6. Mineral oil

You will want to mix in equal amounts of water, then add a tablespoon of liquid soap.  You will then spray on your plants in between watering.  This will kill the caterpillars in the garden but won’t hurt your plants.

Pickle Worm (Diaphania nitidalis)

The pickle worm is an insect from the order Lepidoptera and the family Crambidae.  Found mainly in the Southeastern United States, the pickleworm feeds on the blossom, stems, and developing fruits of summer squash, pumpkins, and occasionally cucumbers and muskmelons.

Among all the cucurbits, summer squash is preferred, and the most heavily damaged plant.

The pickleworm can complete its life cycle in about 30 days.  In the pupa stage the larva is a light brown in color, and tapers to a point at both ends.  This stage lasts about eight to nine days.  The adult moths emerge in spring after overwintering as pupae (undergo change from caterpillar to moth) in semitropical areas such as southern Florida and southern Texas.  The adult moth is a small flashy moth with wide triangular wings and a wingspan of 1 1/4 inches.  The wings are mostly iridescent brown with a central band of semi-transparent yellow. The tip of the abdomen contains a cluster of bush-like hairs.

The adult moth is nocturnal in nature.  They migrate northward to lay eggs on leaves, buds, stems, and fruits of susceptible plants.  The eggs are minute white or yellowish in color and are found in clusters of two to seven.  Eggs hatch in about four days with the female laying some 300 to 400 eggs per female.

Depending on the climate you live in you may see up to four or more generations per year.

Controlling Pickleworms

  1. The pickleworm has several enemies, but none will completely suppress the problem.  Such predators as the soldier beetle and Red fire ants are known to be enemies of the pickleworm.
  2. Because it is so difficult to predict when feeding behavior of the larvae will begin farmers in many areas will use insecticides to control the population.  It is advisable to use insecticides with little residual activity and to apply late in the day to help protect the honeybees from being killed by the insecticide.
  3. Intomopathogenic Nematodes has been shown to effectively suppress pickleworm damage in squash, where they can kill the young pickleworm before it burrows into the fruit.
  4. By planting early, it is often possible to harvest part of the crop before pickleworms appear.
  5. Squash can be used as a trap crop to keep the pickleworm from attacking other plants because the pickleworm prefers squash  over any other cucrbits.
  6. You can use a screen cover to prevent the pickleworm moths from laying eggs but must be removed when plants begin to flower to allow for pollination.
  7. Clean away any old or dead debris, including vines, and fruits after harvest to help reduce populations of pickleworms overwintering in the garden area.
  8. Choosing plants that have a natural resistance to pickleworms can help control the population.  Choose plants such as: Butternut squash, Summer Crookneck squash, or Zucchini (which is somewhat resistant to Pickleworms).
  9. Spraying BT (Bacillus thuringiensis) early in the evening is great solution to control an infestation according to specialists at the University of Florida.
  10. Neem oil and Spinosad, botanical insecticides are effective against the pickleworm through contact toxicity ( a disruption of insect molting and feeding).  Spinosad is derived by microbial fermentation and is effective against pickleworms while being safe to most beneficial insects.
  11. Grub Control, which is a unique organic formulation that can be used as preventative or early treatment against young larvae.

Some natural enemies are:

  • Soldier Beetles
  • Red Fire Ants
  • Trichogramma wasps
  • Braconid Wasps

Check out several images of the pickleworm and the pickleworm moth.

 

Corn Earworm (Helicoverpa zea)

corn earworm
Corn Earworm

The corn earworm is common throughout North America and is a species in the family Noctuidae.  The adult is an inch-long tan moth that lay yellow eggs on leaves underside in the spring.  The caterpillar larvae have alternating light and dark strips that may be green, pink, or brown.  It is in this stage that they do the most damage to plants.  The life cycle can be completed in about 30 days.

The first-generation feeds on the leaves.  Eggs of later generations are laid on corn silk then the emerging caterpillars feed on the slik and the kernels at the tip of the ear just inside the husk.

This same caterpillar may be the same culprit feeding on a number of different plants including:

  • Beans
  • Peas
  • Peppers
  • Potatoes
  • Squash

You may know the corn earworm by many different names.  These names include tomato fruit worm, cotton bollworm, and geranium budworm.

Controlling Corn Earworms

By selecting the best varieties of corn and choosing an early planting date you can have better control over corn earworms.  This is because early and midseason there are fewer corn earworm moths to lay eggs on the silk where as later in the season there are an abundance of moths looking for egg-laying sites.

Beneficial nematodes can be sprayed or injected on silks weekly to control larvae.  Also, you can treat the soil by broadcasting the beneficial nematodes into moist soil well ahead of the first frost.

BT (Bacillus thuringiensis) or Spinosad can be dusted or sprayed on silks.  Continue weekly until tassels turn brown.

Employ beneficial insects and bugs and damsel bugs.  They all will feed on corn earworm eggs and small larvae.

To find information on other insects and bugs in the garden get the guide below.

Get Your Free Garden Guide

For a healthy beautiful garden learn how to tell which insects you want in the garden and which ones you don’t.  It’s a complete guide with over 30 different insects and bugs.  Find out how to spot, control, and destroy them.  Download the guide and receive weekly newsletter from Daisies-n-dollars.com.  Sign up and join us today and get this gardening guide FREE!

 

Concluding,

Caterpillars can be quite damaging to crops in the yard and garden.  Some eat their way through plants while others feed on the fruits and vegetables.  Finding them and destroying them is the best defense.  Or use the many different ways above to control them.  You will want to just get rid of them so they will not destroy your garden plants.

An important tip to keep in mind is to till the soil in early spring and in the fall.  For great deals on rototillers check out a few picks below.

 

 

 

I hope this information on Caterpillars has been informative an beneficial for you.

Happy Gardening from jackie@Daisies-n-dollars.com

 

CATERPILLARS IN THE GARDEN
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