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Beginner

Scientific Names
Brachycorynella asparagi

Identification

• 1 mm long and green.
• Covered with a mealy grey wax.
• Two very short cornicles (tailpipes) on the tip of its abdomen
• Infested plants develop shorter stem internodes and abnormal growth of the cladophylls (needles) at the tips of the branches.
• Asparagus aphids may also transmit several different viruses infecting asparagus plants. This is not usually a significant problem in the Ontario landscape.

Period of Activity
Late-June through August. The asparagus aphid is a periodic pest in Ontario. Outbreaks are usually associated with long periods of hot, dry weather.

Scouting Notes
Carefully inspect 10 groups of 10 plants across the field. While scouting, look for distorted branches and fern tips. Aphids are often difficult to find on the plants. Where damage is suspected, shake the infested fern over a light-coloured surface to dislodge and identify the aphids.

Look for short, bushy shoots at the base of the plants. These shoots often flower after the rest of the field has completed flowering.

Populations often move into the crop from the field edges. Inspect border rows carefully. Large numbers of ladybird beetles may indicate aphid activity in a field.

Thresholds
None established. Treat if the overall field population continues to increase over a period of several weeks.

Advanced

Scientific Names
Brachycorynella asparagi

Identification
The asparagus aphid is 1 mm long, green and covered with a mealy grey wax. It has two very short cornicles (tailpipes) on the tip of its abdomen; however they are very difficult to spot with the naked eye. The asparagus aphid is much smaller than most other aphids found in vegetable crops. Adults found on ferns are commonly wingless, although a winged generation will occasionally develop.

Aphids suck sap from the plant, often under the bracts or at the base of the needles. As they pierce the plant tissue, they inject a toxin into the plant. This results in the abnormal growth of the fern at the site of the wound. This growth may resemble a bonsai tree, or a ball of fern. Feeding also causes stunting of the cladophylls and shortened stem internodes.

Biology
The asparagus aphid feeds only on asparagus. It overwinters as an egg in crop residue and adjoining fence rows. Eggs hatch in early spring as the spears begin to develop. Female aphids give live birth during the growing season. A generation of males is produced in the early fall. The adults mate and lay the overwintering eggs.

Asparagus aphids may also transmit several viruses affecting asparagus, including Asparagus Virus 1 (AV-1) and Cucumber Mosaic Virus (CMV). Aphids transmit AV-1 and CMV to plants within minutes of feeding. Aphids frequently transmit these viruses before insecticides have a chance to kill them.

Period of Activity
Late-June through August. The asparagus aphid is a periodic pest in Ontario. Outbreaks are usually associated with long periods of hot, dry weather.

Scouting Notes
Carefully inspect 10 groups of 10 plants across the field. While scouting, look for distorted branches and fern tips. Aphids are often difficult to find on the plants. Where damage is suspected, shake the infested fern over a light-coloured surface to dislodge and identify the aphids.

Look for short, bushy shoots at the base of the plants. These shoots often flower after the rest of the field has completed flowering.

Populations often move into the crop from the field edges. Inspect border rows carefully. Large numbers of ladybird beetles may indicate aphid activity in a field.

Thresholds
None established. Treat if the overall field population continues to increase over a period of several weeks.

Management Notes

• Aphid populations are normally controlled by natural predators and parasites, including fungi, ladybugs (adults and larvae), lacewings, parasitic wasps and predatory mites.
• The repeated use of pyrethroid insecticides to control asparagus beetle populations may reduce populations of natural predators, resulting in an increase in aphid pressure.
• Aphid-infecting fungi do not survive well in hot, dry weather conditions; often allowing the aphid populations to build.