Asparagus Aphid

family: aphididae
species: Brachycorynella (=Brachycolus) asparagi
common names: asparagus aphid
hosts: asparagus
cultural control methods: remove volunteers
notes: numerous generations between mid-April and mid-October; adults 1mm long

Asparagus Aphid

Brachycorynella (=Brachycolus) asparagi (Mordvilko)
A new pest which attacks the foliage of wild and cultivated asparagus plants in the southern interior of British Columbia. It was first detected in 1979.

Vegetables Attacked:

Asparagus

Life History:

In early spring females hatch from overwintered eggs on the ground as the tips of asparagus spears start developing fern. They feed mainly on the leaflet stems of the foliage and develop through four stages to the adult. Each adult produces numerous generations of females. From early June, both wingless and winged females occur. The latter are capable of flying long distances with suitable winds. In fall, winged males develop and mate with females who lay overwintering eggs on the fern leaflets and stems. The eggs eventually drop to the ground with the fern growth.

Injury:

Feeding by the asparagus aphid will kill or stunt asparagus seedlings and kill or reduce the vigour and yields of mature plants. Adults and nymphs of this aphid feed on the leaflet stems of asparagus fern and congregate near the main stalks. In early spring, nymphs feed on the developing spears until the tips open and fern development begins. During feeding, toxic substances are injected into the plant which shorten the stem internodes and make the foliage a distinct blue-grey. Numerous small shoots with a tufted or bonsai-like appearance develop at the base of the plant. Excessive stimulation of growth buds on the root crowns in the current year results in few, slow-growing, small spears the following year.

Insect:

Winged and wingless asparagus aphids are up to 1 mm long or one-third the length of a green peach aphid and powdery green to grey-green. They are the same color as the plant. Green eggs laid on the foliage later become shiny black. All stages have a pair of short tubes on the back end of the body. The
protruding, tail-like egg laying structure has parallel sides.

Monitoring:

Because this aphid is very small and clings fairly close to the fern, it is difficult to see. Ferns showing witches-broom symptoms can be picked and left in a grocery bag overnight. The next day the ferns can be shaken onto a white surface. If small aphids are observed, they are probably asparagus aphids. They are most likely to be found on plants close to the edge of a field. Continue monitoring throughout the growing season.

Control:

In early spring overwintering eggs of the asparagus aphid can be destroyed on the fern growth by burning or by thorough incorporation into the soil. Removal of volunteer asparagus plants from areas near seedling or producing fields will slow re-infestation. Control aphids on seedling asparagus plants throughout the growing season. Control those on producing plants after harvest when the fern growth starts.