What's Bugging Your Garden?

Reader Contribution by Karen Newcomb
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What’s Bugging Your Garden?

Let’s begin by taking a close look at those pests that do the most damage to your vegetables.  These unwanted marauders divide into four categories.

  1. Beetles, caterpillars, and other pests that chew holes in the leaves of vegetables.
  2. Insects such as aphids, true bugs, and whiteflies that suck plant juices.
  3. Insects that bore into leaves and fruit.
  4. Soil insects that carry on the attack from below.

Most of the insects go through a series of stages.  The beetle, fly, or moth (called the “adult”) lays eggs which hatch a worm (called the larva) that eats everything in sight.  The larva of a beetle is a grub; the larva of a fly is called a maggot; the larva of a moth or butterfly is a caterpillar.  When the larva reaches its maximum size, it enters a nonfeeding dormant stage (the pupa); the adult insect emerges from this pupa.  Both the adult and the larva stages can be extremely destructive.

Chewing Insects

Both beetles and caterpillars are plant gobblers that chew holes in the leaves and fruit of your vegetables.  These holes may be tiny pinpoints or irregular larger holes.  You may even discover that whole leaves have been devoured and entire areas of fruits have been chewed away.

The Beetles

Beetles are obnoxious insects with biting mouth parts and hard front wings that can make short work of your vegetables. 

Asparagus beetles are slender, ¼ inch long, and brownish in color.  Both adults and larvae feed on the new shoots and leaves of asparagus.  As soon as asparagus appears, the beetle lays eggs on the tips.  Within a week the eggs hatch and start to feed.  After 10 to 14 days, these larvae burrow into the ground to become yellow pupae.  The asparagus beetle is found wherever asparagus is grown.

Asparagus beetle    Photo courtesy OrganicGardenInfo.com

Bean leaf beetles  are reddish to yellowish, about ¼ inch long, and have black spots on their backs and black margins around their front wings.  The adult beetles, which are found throughout the United States, eat irregular-shaped holes in the leaves of all kinds of beans and cowpeas.

Bean leaf beetle    Photo courtesy OrganicGardenInfo.com

Blister beetles  are slender gray, black, or striped insects about ¾ inch long.  Only adult beetles injure plants, but swarms of them feed ravenously on the foliage and blossoms of almost any kind of vegetable.  The heavy-jawed larvae do not harm vegetables; instead, they burrow through the soil to find and eat grasshopper larvae.  These beetles reach the destructive stage in early summer, when they emerge to feed in swarms and lay eggs in the soil.  They can raise blisters on the skin if crushed.  Blister beetles are found primarily east of the Rocky Mountains.

Striped Blister beetle       Photo courtesy OrganicGardenInfo.com

Colorado potato beetles are ½ inch long hemispherically shaped insects with black spots on the front parts of their bodies and five black stripes on each wing sheath.  They look like Volkswagens.  The larva of the Colorado beetle is brick-red and has rows of black spots along its sides.  This beetle overwinters in the soil as an adult and then emerges in the Spring to lay eggs on the underside of the leaves.  The eggs hatch in four to n9ne days:  the larvae mature in two or three weeks.  This pest if found everywhere in the United States and southern Canada except in parts of Nevada, Florida, and California.

Colorado potato beetle    Photo courtesy OrganicGardenInfo.com

Cowpea curculios are blackish, chunky beetles about 1/5 inch long.  The grub is whitish, legless, and has a yellow head:  it feeds within the growing pods of cowpeas.  The adult feeds on green snap peas and deposits eggs in holes eaten through the pods.  It is found mostly in the South.

Flea beetles  are tiny bronze or black beetles about 1/16th inch long.  The adult beetles jump like fleas when disturbed and eat what looks like tiny shotholes in the leaves of vegetables.  The white ¼ inch larvae feed on the roots or seeds of germinating plants.  They do the most damage when germination is delayed by cool temperature, giving them time to eat more seeds.  They are found throughout the United States.

Flea beetles    Photo courtesy OrganicGardenInfo.com

Japanese beetles  are ½ inch long, shiny coppery-brown, and have a row of white hair tufts along their bodies.  The section behind the head is metallic green.  The larvae are small white grubs that feed on the roots of grasses.  Although the Japanese beetle attacks 300 different kinds of plants, it damages only a few vegetables.  This pest is found in every state east of the Mississippi River.

Japanese beetle     Photo courtesy OrganicGardenInfo.com

Mexican bean beetles are about ¼ inch long, coppery-yellow with a long black-tipped spine.  Both larvae and adults feed on the undersides of the leaves of beans, cowpeas, and soybeans, skeletonizing the leavesWhen an infestation is severe, this pest will attack the leaves, pods, and stems.  It lays eggs in masses on the underside of the leaves and produces one generation a year in the North, two in the central states, and three or more in the South.  It is found east of the Rocky Mountains.

Mexican bean beetle    Photo courtesy OrganicGardenInfo.com

Spotted cucumber beetles are bout ¼ inch long, yellow and have black spots on their backs.  The adult chews large, irregular holes in foliage.  The larva, known as the southern corn rootworm, tunnels through the roots of cabbages, corn, cucumbers, melons, peas, and other vegetables.  Both adults and larvae spread bacteria that cause cucumber and corn wilts. When the temperature rises above 70 degrees F., the beetles start to feed and lay eggs at the bases of stems.  The newly hatched larvae feed underground.  The spotted cucumber beetle and its close relative, the western cucumber beetle, is found almost everywhere.  Infestations are especially severe in the South.

Spotted cucumber beetle     Photo courtesy OrganicGardenInfo.com

Striped cucumber beetles  are about ¼ inch long, yellow or black, and have three stripes on their wing covers.  The larvae are slender and white, becoming browinish at the ends.  The adults eat leaves, stems, and fruits of tender young plants.  The beetles pass the winter on the ground under leaves or plants.  After feeding on the foliage for several weeks, they lay their eggs in the soil.  The larvae then bore into roots and stems below the soil line.  This pest also spreads cucumber wilt bacteria and cucumber mosaic.

Vegetable weevils (beetles)  are grayish-brown with a light-colored “V” on their wing covers.  The larvae are light green with light yellow heads.  Both adults and larvae feed on the leaves and roots of many vegetables.  The vegetable weevil is found everywhere in the United States.

Vegetable weevil (beetle)       Photo courtesy OrganicGardenInfo.com

Handling the Chewing Insect Problem

The easiest way to get rid of beetles or caterpillars is to pick them off your vegetables and squash them underfoot or drop them in a jar of water.  Let the jar stand for a few hours and then pour the contents into a hole and cover with dirt.  This method works well unless you’re confronted with an all-out attack.

I periodically check the underside of my vegetable plant leaves to check for eggs, if I find any I pinch off the leaf and destroy the eggs.

If the infestation is too much to handle, go for organic chemical methods.  Here are a few that can be purchased at your nursery or through seed catalogs.

Sharp shooter is a spray that is made from citric acid and destroys the wax coating of the insect’s respiratory system.  It is biodegradable and harmless to humans and pets.  Works on a number of insects, including beetles and caterpillars.

Safer’s Insecticidal Soap  is a non-toxic soap concentrate formulated for its insecticidal properties.

Safer Brand 3-in-1 Ready to use Garden Spray works as a fungicide, an insecticide and miticide.  An insecticidal soap with sulfur based fungicide targets and kills many insects including leaf-feeding beetles and caterpillars. 

End All Organic Insecticide spraykills 45 different species from egg to adult.

Cucumber Beetle Lure with Trap  Lures last 3-4 weeks.

Japanese Beetle Trap with Bait  Lures and traps in catch all system.

Diatomacesous Earth Insect Killer  Diatomaceous earth is a powder is skeletal remains of tiny sea creatures.  It is non-staining and widely used in organic gardening.  It causes dehydration within 48 hours of contacting or ingesting. 

Diatom Dust  is also a diatomaceous earth, almost pure silica with 14 trace minerals.

Most of these products, along with others, can be found in your local nursery or seed catalogs.

My next  blog–The Caterpillars (Moths or Butterflies).

Visit www.organicgardenifo.com for more information on bad bugs and good bugs. 

© Copyright by Karen Newcomb
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