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Insects In The Garden

Gardeners grow frustrated as insect pests make a meal out of their fruits, vegetables, flowers and ornamentals. While gardeners are skilled at their craft, it’s nearly impossible to know everything about each type of pest when there are hundreds of insects, each feeding on a different plant, causing different types of damage at different times of the growing season.

For example, cucumber beetles can cause defoliation on plants in the same family, such as squash, zucchini and cumbers. In contrast, aphids suck the sap from plants, such as tomatoes, cucumbers or roses, that belong to different plant families.

In order to know when pest damage is present, it’s critical to recognize what a healthy plant looks like.

When planning the garden, it is also helpful to do some quick research on common pests that may affect your plants. This can help with quicker identification of pests and thus, quicker implementation of control measures.

Identifying a Pest

A pest cannot be controlled without first identifying what it is. Start by asking the following questions to either properly identify the pest yourself or receive identification help from your local WVU Extension Service agent:

  1. What is the affected plant? Some crops, like broccoli, are far more likely to receive pest damage than others, such as lettuce.
  2. What type of damage is present? Is it on the entire plant, leaves, stem or fruit? Some damage can actually be caused by diseases or environmental factors, but it may closely resemble certain types of pest damage.
  3. What stage of the life cycle is the pest/could the pest possibly be? Many butterflies or moths are beneficial, but can cause damage while in their larva stage.

If possible, snap a picture or capture the specimen to make identification easier. Not all pests are damaging – in fact, many insects in the garden setting are beneficial.

Life Cycles

Pests have different forms throughout the course of their life cycle, and not all stages cause the same type of damage or any damage at all. Understanding the life cycle of a pest is also beneficial because timing is helpful in identification. While there’s no one specific date for various life cycles of pests, a rough timeline of the season when each phase appears is useful in knowing when to scout for pest damage.

Some insects undergo complete metamorphosis and have four developmental stages – egg, larvae, pupa and adult. Larvae and adult stages have different forms and usually live in different habitats. Often, the larvae stage is the most harmful stage for garden crops. The most common insects in this category are moths, butterflies, beetles, flies and bees.

In contrast, insects that undergo simple or incomplete metamorphosis have three developmental stages – egg, nymph and adult. An example of these would be squash bugs. Pests with incomplete metamorphosis have the potential to cause damage during both the nymph and the adult stages. They also can be harder to identify, as nymphs of most insect species with incomplete metamorphosis look nearly identical to the adults, except that the adults are larger and reproductively mature. Aphids, whiteflies and stinkbugs are examples of insects with incomplete metamorphosis.

Prevention and Control

Prevention is the key to keeping garden pests under control, but sometimes that is not always feasible. When the weather is suitable for planting, it is also suitable for pests. Integrated pest management (IPM) strategies combine a variety of tactics to keep pest populations under control, with chemicals being a last resort.

Cultural

Cultural controls mean altering the environment to make it undesirable for a pest. This is often the first line of defense because it is the easiest. Cultural control is as simple as maintaining a healthy plant through proper fertilization, irrigation, timing of planting to work around life cycles, selecting resistant varieties and practicing crop rotations

Biological

Biological controls use beneficial organisms to reduce pest populations. Commercial growers may choose to bring in the organism from an outside source. In a garden setting, this is accomplished by the placement of plants that attract a beneficial insect that will prey on a harmful insect, such as using ladybugs to control aphids.

Mechanical and Physical

Man-made manipulation is an easy control option, but it often can be labor intensive. Tilling the soil to allow overwintering eggs to dry out, hand-removing pests and egg masses from plants, using a floating row cover or installing sticky traps are all simple ways to disrupt a routine of pests. Other means of mechanical control include keeping a clean garden and removing any weeds and plant debris where pests have a chance to overwinter. In a garden setting, routine monitoring for pests means quick response time for hand-removal to be an easier task.

Chemical

When an infestation is beyond the help of cultural, biological or mechanical means, chemicals can provide effective, safe control when used correctly and sparingly. Use pesticides as a last resort, and always follow label instructions. The label will provide information on how much product to apply, where to apply and how long to wait before harvesting the product for consumption. Contact your local WVU Extension Service office for advice on what products provide effective control for certain insects.

Striped and Spotted Cucumber Beetles feeding on a cucumber plant

Both Striped and Spotted Cucumber Beetles feeding on a cucumber plant. 

insects feeding on plant

insects feeding on plant

insects feeding on plant

Squash bugs undergo incomplete metamorphosis – eggs, nymph and adult (in order). (Photos by Emily Morrow)


Emily Morrow, WVU Extension Service Agent – Jefferson County