Insect Problems

Insect Problems and Treatments

In this Series

Insect Problems
Fungus Problems
Beneficial Insects
Critter Problems
Azalea Problems
Invasive Plants
Beneficial Insects

Here is a list of common garden insect pests and methods for controlling them. Chemical, mechanical and "home remedy" treatments are covered.

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Spider mites (red, 2-spotted and spruce mites)

Insect Pest

Organic Treatment

Chemical Treatment

Mechanical Treatment

Red Spider Mite

Two-spotted Spider Mite

Dormant Oil Spray in late winter before growth starts.

Insecticidal soaps.

Pepper sprays.

Nicotine sprays

Miticides: chlorpyrifos, diazinon, isofenphos, trichlorfon.

A jet of water can dislodge these pests. Aim upward at the undersides of leaves to get eggs and spider mites. This must be repeated daily.

For indoor plants, increasing humidity helps prevent infestations.

Aphids, sucking and chewing insects

Insect Pest

Organic Treatment

Chemical Treatment

Mechanical Treatment

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Red Aphids

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Tarnished Plant Bug

Dormant Oil Spray in late winter before growth starts.

Insecticidal soaps.

Pepper sprays.

Nicotine sprays

Borax around house foundations and entries

Aphids, sucking and chewing insects:

Semi-organic insecticides: pyrethrins, rotenone.

Non-organic insecticides: permethrin, malathion, carbaryl.

A jet of water can dislodge aphids. This must be repeated.

Beetle, Grubs and Cutworms

Insect Pest

Organic Treatment

Chemical Treatment

Mechanical Treatment

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Adult Japanese Beetle

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Beetle Grub

Adult Beetles - no organic control. See mechanical control

Grubs and cutworms

Milky Spore Disease, Bacillus popilliae Dutky. Get Milky Spore from Gardener's Supply

Parasitic Nematodes are commercially available. Use products that contain strains of Steinernema carpocapsae (Biosafe, Biovector, Exhibit, Scanmask) and Heterorhabditis spp.

Adult Beetles

Insecticides: acephate, carbaryl, chlorpyrifos, malathion, methoxychlor, and rotenone plus pyrethrin. During the heavy adult activity periods, sprays may be needed every 5 to 10 days.

Grubs and Cutworms:

Diazinon, chlorpyrifos drenches or granules watered into soil.

Adults: Hand pick or use traps - several traps using a floral lure and sex attractant are available. Grubs and Cutworms: Use collars around seedlings.
Plant non-attractive plants: ageratum, arborvitae, ash, baby's breath, garden balsam, begonia, bleeding heart, boxwood, buttercups, caladium, carnations, Chinese lantern plant, cockscomb, columbine, coralbells, coralberry, coreopsis, cornflower, daisies, dogwood (flowering), dusty-miller, euonymus, false cypresses, firs, forget-me-not, forsythia, foxglove, hemlock, hollies, hydrangeas, junipers, kale (ornamental), lilacs, lilies, magnolias, maple (red or silver only), mulberry, nasturtium, oaks (red and white only), pines, poppies, snapdragon, snowberry, speedwell, sweet pea, sweet-William, tuliptree, violets and pansy, or yews (Taxus).

Root and Vine Weevils
Insect Pest	Organic Treatment	Chemical Treatment	Mechanical Treatment
Root Weevil Larvae Adult Vine Weevil	Parasitic nematodes (see above) especially Steinernema and Heterorhabditis spp.	Insecticidal soil drench: Works only with systemic, persistent insecticides like chlorpyrifos, methoxychlor, endosulfan or lindane. Complete drenching of potted plants has been effective. Foliar Insecticides: Adults are active after dark, the most common method of control is to place a stomach poison on susceptible plant foliage. Because adults are active for a long period, several sprays may be needed. Early applications are encouraged so that adults are affected prior to their egg laying period (see list above)	Habitat Modification - Soil moisture and mulching increase weevils. Remove excessive mulch layers and do not water plants unless necessary. Provide for adequate drainage of soil around plants.
Scale
Insect Pest	Organic Treatment	Chemical Treatment	Mechanical Treatment
Scale on branch	Dormant Oil Spray in late winter before growth starts Nicotine spray in spring, summer	Malathion or dimethoate spray in spring/summer for annuals and perennials, fruit trees. Systemic Insecticide spray for ornamental trees and shrubs - e.g. chlorpyrifos, oxydemeton-methyl, dimethoate, methoxychlor	None
Mealy Bugs
Insect Pest	Organic Treatment	Chemical Treatment	Mechanical Treatment
Mealybug	Dormant Oil Spray in late winter before growth starts. Insecticidal Soap Spray in spring/summer	Systemic Insecticide Sprays: dimethoate, oxydemeton-methyl Non-systemic Insecticide Sprays: Dichlorvos.	Jet of soapy water may dislodge minor infestations.
Caterpillars and Moths
Insect Pest	Organic Treatment	Chemical Treatment	Mechanical Treatment
Tent Caterpillars	Bacillus thuringiensis (Bt) will work on tent and other nest-making caterpillars. Make applications to the plant foliage while the larvae are small. Tanglefoot around the tree/shrub trunks to keep larvae from crawling up	Insecticide Sprays: carbaryl, malathion, rotenone, trichlorfon	Destroy Egg Masses and Nests - The egg masses are easy to spot after the leaves have dropped in the fall, or during winter and early spring. Simply clip off and crush or dispose.
Whiteflies and Fungus Gnats
Insect Pest	Organic Treatment	Chemical Treatment	Mechanical Treatment
Whiteflies Fungus Gnats	Yellow sticky traps Nicotine Spray Organic Insecticides: Sprays containing pyrethrum or neem give the best control. Both the surface and the underside of the leaf need to be covered and during the summer, you must spray every 5 days. Bacillus thuringiensis isrealiensis (BTi): Beneficial Nematodes	Insecticidal Sprays: malathion, pyrethrum, resmethrin, rotenone	Sticky traps: Dichlorvos. Check new plants before purchasing carefully for tiny white or black flying insects. Vacuum! Yes, just vacuuming them out of the air will get the numbers down considerably! Sand: Apply a layer of course sand to the soil surface to discourage fungus gnats.
Slugs and Snails
Insect Pest	Organic Treatment	Chemical Treatment	Mechanical Treatment
Slug	Body-piercing substances: sprinkle these under and around your plants: •Diatomaceous Earth •Crushed egg shells •Crushed oyster shells	Metaldehyde (pellets or granules) Ferric Phosphate (pellets or granules) - this is considered "organic" too.	Do not use mulch, remove debris. Copper tape around garden beds. Shallow saucers of beer (empty daily) Lay boards, rolled-up newspapers or pipes near plants, lift daily and dispose of slugs. Midnight patrols with flashlight and pail of hot soapy water for drowning. Poultry! especially ducks pig out on slugs and snails.
Ants
Insect Pest	Organic Treatment	Chemical Treatment	Mechanical Treatment
Ant	Control aphids Yellow sticky traps Grits! Yes, ants gobble up good old fashioned grits and blow up REAL good. Coffee! never2many's trick: sprinkle a few tablespoons of instant coffee over the hill area(s) - or you can break through the hills into the tunnels and apply. Repeat 3-4 times - this even works on fire ants!	Outdoors: Use a perimeter spray containing Dursban, Diazinon or Baygon, treating the lower 2 feet of the foundation and out 3 feet into the soil, especially around windows, doors, etc. with the insecticide mixed in water, preferably as a wettable powder formulation, to avoid plant injury. Commercial bait syrups such as borax (Terro), hydramethylnon (Maxforce), methroprene (Pharorid), bendiocarb (Ficam), propoxur (Baygon) and sulfluramid (Pro-Control). will kill ants that feed on sweets.	Sticky traps: Dichlorvos
For detailed information on organic insecticides, visit this link. See this link for all popular pesticides for general home, nursery and landscape use.
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