How to Manage Pests

UC Pest Management Guidelines

DESCRIPTION OF THE PEST

The wingless summer form of the willow carrot aphid is pale green with the cornicles, cauda (tail-like structure), and legs pale to slightly dusky. They are medium-sized aphids with rather elongate oval-shaped bodies that are flattened front to back. The upper surface of the body may be roughened by numerous small depressions. The wingless forms have a second tail-like process called the supracaudal process directly above the cauda giving the aphid the appearance of having twin tails when viewed with a hand lens. This supracaudal process may be triangular or fingerlike in shape.

The winged forms have a black head and thorax. The abdomen is pale green with dark areas on the sides and dark bands on the top. The antennae are black. The legs are pale in color and black at the tips. The cornicles are somewhat swollen near the tip.

DAMAGE

Willow carrot aphid is primarily of concern because of its efficiency in vectoring a number of serious virus diseases. It transmits carrot motley dwarf, carrot red leaf, and parsnip yellow fleck. It is also a vector of celery mosaic, sugarbeet mosaic, and cauliflower mosaic virus. It seldom reaches numbers that trigger the need for chemical intervention.

MANAGEMENT

Biological Control
Little is known regarding the parasites of willow carrot aphid. The presence of bloated mummies indicates parasite activity. Predators such as green lacewing larvae, lady beetles, and syrphid fly larvae prey on this aphid as well as on other aphid species.

Cultural Control
Sanitation is important in curbing the spread of the viruses that this insect vectors. Disc all crop residues under as soon as harvest is complete. Keeping fields, ditch banks, and fence lines weed free may also help in reducing virus inoculum.

Organically Acceptable Methods
Biological and cultural controls are acceptable for use on organically grown produce.

Monitoring and Treatment Decisions
No treatment thresholds have been established. Chemical treatments are not effective in preventing virus transmission and this aphid rarely builds up in numbers high enough to cause economic damage by direct feeding.

PUBLICATION

UC IPM Pest Management Guidelines: Carrot
UC ANR Publication 3438
Insects
E. T. Natwick, UC Cooperative Extension, Imperial County
D. R. Haviland, UC IPM Program, Kern County
C. G. Summers, Entomology, Kearney Agricultural Center, Parlier
Acknowledgment for contributions to Diseases:
W. E. Chaney, UC Cooperative Extension, Monterey County

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