Garden Insects: Friend or Foe?

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Deep in our gardens, insects hunt and forage for food, battle with predators and prey, and hatch new life from eggs so beautiful they could pass as art while others give birth to live young. Some help our gardens thrive and others ravage them, but they all play an important role in the garden’s ecosystem. We spoke with Karey Windbiel-Rojas, associate director for urban and community integrated pest management at the University of California Statewide Integrated Pest Management Program, and she helped identify 10 common garden insects and shared the following tips to help manage them.

Employ integrated pest management. In a garden’s ecosystem, every insect has a value and place. The concept of IPM is not to eliminate every garden pest, but to keep them controlled at a level where they don’t cause extensive damage. Garden pests are food for beneficial insects, bats and birds.

Beware of broad–spectrum insecticides. These insecticides don’t discriminate. They can kill beneficial bugs including earthworms, bees and other pollinators, says Windbiel-Rojas. Be sure to read labels before using any insecticide.

Identify your insects first. If it’s a pest, choose the least toxic approach that gives you good results, says Windbiel-Rojas. For help identifying pests, contact the UC Master Gardeners of Sacramento County at (916) 876-5338 or use the UC IPM’s pest identification tools, including the Natural Enemy Gallery, at ipm.ucanr.edu.

Consider nontoxic control measures. Large pests like hornworms can be removed by hand (and make a great treat for birds). Aphids can often be controlled by spraying nontoxic, soapy water on plants. Row netting over young plants works as an effective barrier against some pests, and neem oil, a naturally occurring pesticide, controls others.

Practice appropriate plant care. Plants that are well cared for can better withstand a little pressure from feeding pests. For starters, Windbiel-Rojas recommends making sure watering and sun exposure match plants’ requirements. Adding compost to the soil provides nutrients for plants to grow and thrive.

Keep your garden clean. Remove cuttings and leaf litter to reduce hiding places for pests, and keep your tools clean to minimize the spread of pests and diseases in the garden.

Remember your kindergarten biology. Caterpillars turn into moths and butterflies, which are pollinators. But often, gardeners consider all caterpillars pests because they chew through leaves. According to Windbiel-Rojas, a good rule of thumb is to leave caterpillars on ornamental plants as long as the damage isn’t intolerable (they’re a species we enjoy as pollinators in our wildlife gardens) but remove those that are found on fruit and vegetable plants, like hornworms.

Attract the good guys. Grow a variety of plants that produce nectar and pollen. Adult beneficials generally feed on nectar and pollen, but their young feed on pests. Native plants such as common yarrow, ceanothus, sage and California fuchsia have evolved with our native pollinators, making them ideal selections.

The Garden Pests

The insects below are piercing/sucking insects. They cause damage by piercing the plant or fruit and sucking up the nutrients.

Aphids
Aphids. Photo by Jennifer Berry Junghans
  1. Aphids—These garden pests are particularly attracted to tender and overwatered plants. Ants feed on the honeydew aphids produce and in turn protect the aphids from predators.
  2. Leaf–footed bugs—Comical–looking orange–and–black nymphs (young insects) cluster together, making them easy to identify. Named for theleaflikestructure on the adults’ hind legs, these insects pierce fruit like tomatoes, pomegranates and stone fruits.
    insects
    Leaffooted Bug Nymphs. Photo by Jennifer Berry Junghans
    Leaffooted Bug Adults
    Leaffooted Bug Adults. Photo by Jennifer Berry Junghans

    insects
    Leaffooted Bug Adult by Jennifer Berry Junghans

  3. Stinkbugs (photographed: brownmarmoratedstink bug)—These squatty bugs feed on developing fruits, nuts and vegetables, leaving scars, depressions and discoloration. They can ruin the fruit’s texture.

    Brown Marmorated Stink Bug
    Brown Marmorated Stink Bug. Photo by Jennifer Berry

  4. Scale (photographed: brown soft scale)—These creatures are often overlooked as bumps or growths—commonly found oncitrus trees, for example. Some scale produce honeydew, which is so attractive to ants that they will attack beneficial insects that prey on scale.

    insect
    Photo by Jack Kelly Clark, University of California Statewide IPM Program

  5. Whiteflies (photographed: greenhouse whitefly)—These tiny flies are difficult to discern with the naked eye but can easily be recognized by an aggregation of white slivers on leaves and the presence of sticky honeydew.

    whiteflies
    Whiteflies. Photo by Jack Kelly Clark, University of California Statewide IPM Program

Beneficial Insects

Beetle Larva
Beetle Larva. Photo by Jennifer Berry Junghans
Lady Beetle Pupa
Lady Beetle Pupa, Photo by Jennifer Berry Junghans
Lady Beetle Adult
Lady Beetle Adult. Photo by Jennifer Berry Junghans
  1. Lady beetles (photographed: multicolored Asian lady beetle)—Commonly called ladybugs, these insectsprey onaphids and scale. Note the spiny-looking larval stage of the lady beetle. It’s often mistaken for a garden pest.
  2. Assassin bugs (photographed: leafhopper assassin bug)—These predators come in a variety of shapes and colors,but all stab their prey, such as aphids, caterpillars and leafhoppers, and inject them with venom.

    Leafhopper Assassin Bug
    Leafhopper Assassin Bug. Photo by Jennifer Berry Junghans

  3. Green lacewings—Easily identifiable with brightgreen bodies, large, round eyesand translucent wings, adults feed on nectar and pollen, but their larvae feed on a majority of garden pests. insects
  4. Soldier beetle—These red–and–black adults often feed on aphids but also consume pollen and nectar. Larvaedevelop in the soil and eat eggs and larvaeof other insects.

    soldier beetle
    Soldier Beetle. Photo by Jennifer Berry Junghans

  5. Spiders (photographed: orb weaver)—Spiders can be a gardener’s best friend by eating an abundance of garden pests. “If you see them in your garden, leave them be and applaud their presence,” says Windbiel-Rojas.

    spider
    Photo by Jennifer Berry Junghans

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