Gardeners water, feed, pinch, prune, and putz so we can enjoy the fruits of our labor–not to invite unwanted pests. Learn to identify and prevent some common summer garden pests: spider mites, sow bugs, stink bugs, whiteflies, yellow jackets, and budworms.
Spider Mite
Description: Only 1/20 inch long, adult spider mites have eight legs and an oval body with two red eyespots near the head.
Damage: Mites cause damage by sucking cell contents from leaves. Damage may initially show as small dots or specks on the leaves; as the problem worsens, leaves may turn yellow or red and drop off. Frequently, there are also webs that cover leaves, twigs, and/or fruit.
Common Hosts: A large variety of fruits, vegetables, and ornamental plants.
Prevention: Water-stressed plants are easy targets for spider mites, so adequate irrigation is critical. In some cases, spider mites can become a problem after insecticides have been applied. This is a result of insecticides removing the mites’ natural enemies--but certain insecticides may also stimulate mite reproduction.
Control: Sprays of water, insecticidal oils, or soaps can be used to manage. Additionally, spider mites have many natural enemies that can help eliminate the problem.
Sow Bug
Description: Rounded bodies, dark gray to white in color, approximately ¼- to ½-inch long, with 7 pairs of legs, and 2 pairs of antennae. Unlike the pill bug which looks very similar, sow bugs cannot roll into a ball.
Damage:Sow bugs are scavengers and will feed on decomposing organic matter and/or young plants and seedlings, typically only coming out at night, unless their shelter is disturbed.
Common Hosts: Sow bugs prefer damp areas and feed on decaying vegetation in flower beds, gardens, landscapes, etc.
Prevention: Eliminate the sow bugs hiding places by removing excess mulch, leaves, and grass clippings.
Control:Use Neem oil, or sprinkle diatomaceous earth around the base of pots. Natural predators include frogs, toads, spiders, lizards, and small mammals.
Stink Bug
Description: Approximately half-inch-long grayish-brown shield-shaped bugs.
Damage: Stink bugs have sucking mouth parts that they use to feed on fruit, leaving indentations or discolored spots behind.
Common Hosts: A large variety of fruits and vegetables.
Prevention: Eliminate weeds. Stink bugs overwinter on weeds, so eliminating weeds in your landscape will eliminate their main food source in the winter and keep populations down.
Control: Planting a variety of flowers that bloom during all seasons to help attract natural predators such as green lacewings, assassin bugs, and damsel bugs. Chemical controls are generally not very effective against these summer pests.
Whitefly
Description: Extremely small (~1mm) white, flying insects.
Damage: Whiteflies have sucking mouth parts that they use to suck the juices out of a plant’s foliage. Damage appears as many small pale-colored dots on the foliage known as ‘stippling’. Occasionally leaves will look crisp or dried up, and may fall off completely. They also leave behind a sticky excrement which can cause sooty mold on the leaves.
Common Hosts: Almost all plants are susceptible, some species prefer specific hosts. They breed almost year-round in California although warm weather increases populations of these pests.
Prevention:
Attract beneficial insects. Planting a variety of flowers that bloom at all times during the year will attract natural enemies of whiteflies, such as Ladybugs and Green Lacewings.
Apply reflective mulch. Whiteflies can become confused when plants are mulched with a reflective material.
Apply Bonide® All Seasons Horticultural Oil. Follow directions for application rates and schedule.
Control: Insecticidal soaps and Neem oil can be an effective method of smothering the insects to keep populations down, however, it is difficult to completely eradicate whiteflies by this method alone. Sticky traps placed near the affected area can also help reduce populations, be sure to replace them often.
Yellowjacket
Description: Medium-sized flying insects with segmented torsos and yellow and black stripes. They are distinguished from bees by their aggressive behavior and hairless bodies.
Damage: Yellowjackets, as well as many other species of social wasps, can be considered both a beneficial insect and a pest. If aggravated, they can sting people or animals.
Common Hosts: In early summer, they usually seek out sources of protein and feed on other insects, making them beneficial. In the late summer, they are attracted to sugar and can become a nuisance by feeding on dropped fruit, picnics, pet food, and trash cans.
Prevention: When you see a nest beginning to form, eliminate it with chemical sprays as soon as possible before it gets too large. Also, clean up dropped fruit, and seal trash cans to eliminate their food sources.
Control: Pheromone-based traps are the most effective method against yellowjacket infestations. Be sure to replace the lure, and empty the traps frequently. Chemical sprays applied to the nests can be effective, but take caution to wear protective gear, as agitated wasps are particularly aggressive.
Budworm
Description:Small (1mm-1cm) caterpillars, can be variable in color ranging from green to brown.
Damage: Small holes in flower buds, occasionally tiny black excrement that resembles poppy seeds are present.
Common Hosts: Geraniums, petunias, and many agricultural crops such as tobacco and cotton.
Prevention:
Attract beneficial insects. Natural predators of budworms include the Bigeyed bug.
Remove by hand. They can be hard to control by chemical methods because they tend to hide inside the flower buds and be difficult to reach.
Control: Bacillus thuringiensis or B.T. is a natural bacteria that is toxic to all types of caterpillars. Unfortunately, the caterpillars must consume it in order to perish, so the damage will continue for a while after treatment. Use Monterey B.t. as directed.
