grape Flea Beetle
Beginner
Scientific Name
Altica chalybea
Identification
Adult
- 5 mm long
- Dark metallic, greenish-blue or steel blue colour
- Able to jump
- Newly hatched larvae are dark brown but as they grow their colour lightens
- Light brown, 7-9 mm long when mature
Eggs
- Cylindrical about 1 mm long
- Yellow to orange
- Laid under the loose bark of the canes and near the buds
- As foliage develops some eggs are laid on the upper side of the leaves but none are deposited on the underside
Damage:
- A few to many buds on a cane may be injured by the adult when it chews through the ends and sides of swelling buds
- A circular hole in the chewed buds and no shoots are produced
- Yield loss when primary and secondary bud are injured
- Larvae feed on young leaf tissue but avoid veins; damage is typically limited to several leaves and vines
Often Confused With
Climbing cutworm injury: larvae feed at night, not visible during the day
Period of Activity
Adults emerge late April through June. After buds are over 2 cm long, grape flea beetles usually do little damage.
Scouting Notes
Monitoring as vines start to grow in the spring is important especially if an area has been infested by flea beetles in previous years. Vineyard edges near woods where alternate hosts for the beetle may be growing (wild grape and Virginia creeper) are prime areas for grape flea beetles. Abandoned vineyards can also be significant sources of this pest.
Threshold
In Michigan, an action threshold of 2 percent damaged buds is recommended in juice grapes, and this can be determined by sampling 10 buds on each of 10 vines spread through the vineyard. Thresholds in wine grapes may be lower due to the higher value of the crop, but there has been little formal research on this topic. Still, it is clear that the potential damage justifies scouting and management if flea beetle damage is detected.
Advanced
Scientific Name
Altica chalybea
Identification
Adult
- 5 mm long
- Dark metallic, greenish-blue or steel blue colour
- Able to jump
- Newly hatched larvae are dark brown but as they grow their colour lightens
- Light brown, 7-9 mm long when mature
Eggs
- Cylindrical about 1 mm long
- Yellow to orange
- Laid under the loose bark of the canes and near the buds
- As foliage develops some eggs are laid on the upper side of the leaves but none are deposited on the underside
Damage:
- A few to many buds on a cane may be injured by the adult when it chews through the ends and sides of swelling buds
- A circular hole in the chewed buds and no shoots are produced
- Yield loss when primary and secondary bud are injured
- Larvae feed on young leaf tissue but avoid veins; damage is typically limited to several leaves and vines
Often Confused With
Climbing cutworm injury: larvae feed at night, not visible during the day
Biology
Grape flea beetle overwinters as an adult. They start to emerge at bud swell. The greatest injury occurs during prolonged cool springs with slow bud growth. During their spring feeding, grape flea beetle females lay their eggs on the canes and later die.
Period of Activity
Adults emerge late April through June. After buds are over 2 cm long, grape flea beetles usually do little damage.
Scouting Notes
Monitoring as vines start to grow in the spring is important especially if an area has been infested by flea beetles in previous years. Vineyard edges near woods where alternate hosts for the beetle may be growing (wild grape and Virginia creeper) are prime areas for grape flea beetles. Abandoned vineyards can also be significant sources of this pest.
Threshold
In Michigan, an action threshold of 2 percent damaged buds is recommended in juice grapes, and this can be determined by sampling 10 buds on each of 10 vines spread through the vineyard. Thresholds in wine grapes may be lower due to the higher value of the crop, but there has been little formal research on this topic. Still, it is clear that the potential damage justifies scouting and management if flea beetle damage is detected.
Management Notes
Grape flea beetle is normally a minor pest but it can cause significant damage in some cases if enough beetles are present; a cool spring with slowly developing vines allows more time for the beetles to cause damage.
