7 Destructive Garden Insect Pests – 2024 Guide

Is your garden looking rough or like it’s wilting? Chances are you’ve got an insect infestation happening that if not addressed will kill your plants. There are a variety of pests that damage your garden and plants, but effective DIY pesticides to treat these insects at valpak.com To learn more about the appearance, feeding habits, and ways to control the seven most common garden pests, read below.

1. Aphid

Source: gardentech.com

Aphids are generally under ¼-inch, soft-bodied insects that are nearly invisible to the naked eye. Various species can appear black, brown, white, gray, yellow, light green, and some may have a waxy or woolly coating. They have pear-shaped bodies with long antennae.

Aphids usually feed in large groups and on a wide variety of plants. Different species of aphids can be specific to certain plants. For example, some species include bean aphids, cabbage, and potato aphids.

These critters can survive in almost any USDA Hardiness Zone and easily find their way into gardens. Because they multiply quickly, it’s important to get them under control before reproduction starts. The good news is that they tend to move rather slowly.

Companion planting, bringing in beneficial insects, and spraying dormant horticultural oil are a few ways to prevent aphids. Diatomaceous earth can be applied when plants are not in bloom, but soapy water can be applied to the plants every few days during any season.

2. Cutworm

source: wikipedia.org

Cutworm is the name used for the larvae of several species of adult moths. These caterpillars do the most damage early in the gardening season when they emerge from hibernation.

Cutworms chew through plant stems at the base. They primarily feed on roots and foliage of young plants, and will even cut off the plant from underneath the soil. In most cases, entire plants will be destroyed; they do a lot of damage in no time at all. Even if only the bottom of the plant is destroyed, the top will often wither and die.

Cutworms are common on a wide variety of vegetables like cabbage, corn, lettuce, and any new seedlings. To identify them, try patrolling your garden in dusk and evening hours when cutworms will begin to feed.

Some ways to eliminate cutworms are by making plant collars, applying an insecticide in the late afternoon, and sprinkling used coffee grounds or diatomaceous earth around the plants.

3. Japanese Beetle

Source: almanac.com

Adult Japanese beetles are oval-shaped, with males being somewhat smaller than females. This species can be identified by its metallic green color with bronze or coppery wing covers, and six pairs of white hairs around the side of the abdomen which distinguishes them from all other similar looking beetles.

While adult Japanese beetles feed on plant and tree foliage, the larvae, known as grubs grow and mature underground consuming grassroots. Grubs can cause considerable damage to lawns, golf courses, pastures, and turf, adult beetles consume the foliage of several tree species including poplar, walnut, birch, willow, elm, and apple. They also consume the foliage from grapes, corn, blackberry, raspberry, roses, asparagus, and soybean.

Japanese beetle management should address adult and larval stages through an integrated approach including physical removal on cool mornings when adults are less active, trapping with baited commercial or homemade traps, cultural control by reducing irrigation and removal of host plants, and biological control with the use of wasps, ants, and ground beetles. Small animals like skunks, moles, and raccoons also feed on grubs but may cause significant turf damage in doing so.

4. Tomato Hornworm

Tomato Hornworm
source: sanmarcosrecord.com

The tomato hornworm is most recognizable in its larvae or caterpillar stage. This caterpillar grows to a length of 4 to 5 inches, can be green with V-shaped white markings on its sides, and has a prominent horn protruding from its hind end that’s normally black.

Tomato hornworms feed on the foliage and sometimes green fruit of tomato, pepper, potato, and eggplant. Hornworm adults (moths) are nectar feeders and do not damage the plant.

To control tomato hornworms, handpick them from the plants, and till the soil after harvest. These caterpillars pupate beneath the soil and tillage can destroy the majority of them.

However, if your plants are host to several larvae (one or more per plant), insecticidal treatment is recommended. Synthetic pyrethroids, carbaryl, and mixtures of Bacillus thuringiensis are effective in controlling small hornworms.

There are natural factors that help control hornworms. Eggs and small larvae often fall victim to predatory insects, such as ladybugs, lacewings, wasps, and yellowjackets.

Hornworms are also parasitized by small wasps. Hatching larvae from wasp eggs consume the hornworm’s internal organs and fluids. Then, as adult wasps emerge from their cocoons attached to the host’s body, it dies.

These parasitized hornworms should be left to propagate beneficial wasps. The wasps that emerge will seek other hornworms to parasitize.

5. Slug

Source: saga.co.uk

Slugs are essentially shell-less snails, spineless, slimy, and basically a stomach on a foot. As slugs slowly navigate through a garden, they leave a slime trail, fecal droppings, and damaged foliage behind them.

Slugs can consume several times their own body weight each day. Unlike snails, slugs spend much of their time underground and are known to attack African violets, asters, dahlias, dogwood, hibiscus, ivy, orchids, poppies, primroses, rhododendrons, and roses.

Bulbs and tubers such as calla lilies, lilies, gladioli, irises, narcissus, and tulips can be damaged as well. Young evergreens can also be heavily damaged or killed by slug attacks.

Controlling slugs can be accomplished by physically removing them, setting baited traps, and by releasing predatory snakes, spiders, birds, other slug species, and predatory beetles. Natural control occurs with flooding or freezing conditions. As harmful parasites may be carried by slugs, it is recommended to use gloves when physically handling them.

6. Scale

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Adult scales and nymphs (youth) of most species are circular or oval, wingless, and lack recognizable body parts. Some scales alter their appearance as they grow, and select species have males and females that differ in shape, size, and even color.

Adult males are seen rarely and are tiny, delicate, white to yellow insects with a single pair of wings and long antennae. Some scale species do not have males, and females are left to reproduce without mating.

Armored and soft scales are the most common families. Armored scales have a flat plate-like cover, and do not produce honeydew. Soft scales are typically larger and more rounded at maturity than armored scales.

Many scale species weaken a plant and stunt its growth when heavily infested. Infested plants will appear to be water-stressed with leaves turning yellow and dropping prematurely. Heavily infested plant parts may die. As honeydew is produced by soft scale, sooty mold and ants can become a nuisance, even when the scale is not harming the plant.

Many scale species are well controlled by beneficial predators and parasites. Exceptions occur when natural enemies are disrupted by protective ants, dust, or the use of some broad-spectrum insecticides.

The well-timed and precise application of horticultural oil during late winter to early summer can result in excellent control of most scale species. Replace plants that are repeatedly attacked or that perform poorly with pest-resistant species and cultivars.

7. Whitefly

source: gardeningknowhow.com

Greenhouse, silverleaf, banded-wing, and citrus whitefly adults are covered in a white, waxy powder resembling small moths. The adult female reaches about 1/16 of an inch in length.

Whiteflies attack and feed on more than five hundred species of plants. Ornamentals such as poinsettia, hibiscus, ivy, daisy, verbena, and garden chrysanthemum are especially susceptible to whitefly damage.

Whitefly feeding is accomplished by injecting enzymes and removing the plant’s phloem, simultaneously reducing the vigor of the plant.

Honeydew secretions promote the growth of sooty mold while feeding damage symptoms include stem branching, leaf yellowing, and premature shedding. High population levels of whiteflies typically result in plant death. Some whitefly species can transmit harmful pathogens or viruses from plant to plant.

Chemical controls including insecticides and insect growth regulators (IGR) along with biological controls like predators (example – lacewing larvae), parasitoids, or pathogens should be used in conjunction to control whitefly infestations.

Your Garden And Pest Control

Don’t allow your garden to fall victim to insect infestations when they can be easily controlled in the beginning stages.

In this article, you discovered how to identify seven species of garden pests, their feeding habits, and how to control them.

Your plants will die if you allow a garden infestation to go unchecked.