Tiny, pear-shaped; long antennae; two tubes projecting rearward from abdomen.
Host/Range: Most fruits and vegetables, flowers, ornamentals, shade trees. Found throughout North America.
Damage: Aphids suck plant sap, causing foliage to distort and leaves to drop; honeydew excreted on leaves supports sooty mold growth; feeding spreads viral diseases.
Control: Wash plants with strong spray of water; encourage native predators and parasites such as aphid midges, lacewings, and lady beetles; when feasible, cover plants with floating row cover; apply hot-pepper or garlic repellent sprays; for severe problems, apply horticultural oil, insecticidal soap, or neem.
2. Cabbage Maggot
Adults: 1⁄4-inch gray flies. Larvae: white, tapering maggots.
Host/Range: Cabbage-family crops. Found throughout North America.
Damage: Maggots tunnel in roots, killing plants directly or by creating entryways for disease organisms.
Control: Apply floating row covers; set out transplants through slits in tar-paper squares; avoid first generation by delaying planting; apply parasitic nematodes around roots; burn roots from harvested plants; mound wood ashes or red pepper dust around stems.
Soft, segmented larvae with distinct, harder head capsule; six legs in front, fleshy false legs on rear segments.
Host/Range: Many fruits and vegetables, ornamentals, shade trees. Range varies with species.
Damage: Caterpillars chew on leaves or along margins; droppings soil the produce; some tunnel into fruits.
Control: Encourage native predators, parasites; hand pick; apply floating row covers; spray with Bt (Bacillus thuringiensis) or spinosad.
Fat, 1-inch-long, gray or black segmented larvae; active at night.
Host/Range: Most early vegetable and flower seedlings, transplants. Found throughout North America.
Damage: Cutworms chew through stems at ground level; they may completely devour small plants; most damaging in May and June.
Control: Use cutworm collars on transplants; delay planting; hand pick cutworms curled below soil surface; scatter bran baits mixed with Btk (B.t. var. kurstaki) and molasses before planting.
5. Japanese Beetle
Adults: metallic blue-green, 1⁄2-inch beetles with bronze wing covers. Larvae: fat, white grubs with brown heads.
Host/Range: Many vegetables and flowers, small fruit. Found in all states east of the Mississippi River.
Damage: Adults skeletonize leaves, chew flowers, may completely defoliate plants; larvae feed on lawn and garden plant roots.
Control: Shake beetles from plants in early morning; apply floating row covers; set out baited traps upwind of your garden on two sides and at least 30 feet away; apply milky disease spores or Herterorhabditis nematodes to soil; spray beetles with insecticidal soap.
Infographic with Pest Images
Pest Information Source: OrganicGardening.com