1) Grape Berry Moth
- The grape berry moth is the most common and destructive of all grape insect pests.
- Adult moths lay eggs near bloom and the larvae that hatch from these feed on young berries.
- As the berries enlarge, the larvae bore a small hole in the side of the berry and tunnel through the interior, causing the berry to drop early.
- Later in the season, as ripening begins, the wounds caused by berry moth larvae are readily colonized by rot organisms that can then invade and destroy part or all of the fruit cluster.
2) Grape Flea Beetles
- Grape flea beetles are small (3/16-inch), shiny metallic, bluish-black insects that jump like a flea when disturbed. Upon emerging from hibernation in the spring, the adult beetles feed on swelling and opening grape buds, leaving what appears as a large, round hole in the side of the bud.
- Flea beetle damage is greatest where vines are located near wooded areas and following mild winters.
- Where populations are very high, up to 40 percent of the buds may be ruined. After bud break, however, little significant damage occurs.
3) Japanese Beetles
Japanese beetles tend to congregate and feed on grape shoot-tip leaves in large numbers. The adult beetles are present for only a short time in early July. Although their damage is often quite visible, it seldom is severe enough to damage the crop.
- Sweep Japanese beetles into a bucket of soapy water.
- Where feeding is severe, use a labeled organic or chemical insecticide.
- Avoid Japanese beetle traps because they tend to attract large numbers of beetles, which can lead to additional plant damage.
- Phylloxera is an aphid-like sucking insect with both root (which causes the most plant damage) and leaf-feeding stages.
- Root damage can be prevented by using only the recommended resistant rootstocks or planting American-type grapes.
- The leaf-feeding stage induces the formation of many tiny galls on the shoot-tip leaves, which can cause them to become stunted and severely deformed.
- This damage, like that of Japanese beetles, is quite visible but causes little overall stress to the plant unless populations are very large.