Tuberolachnus salignus

Giant willow aphids. Photo: Mariusz Sobieski, Bugwood.
Scientific Name: Tuberolachnus salignus
Common Name: Giant Willow Aphid
Growing Degree Days (GDD's): 1644–2271 GDD's, Base 50F, March 1st Start Date (Source: Robert Childs, UMass Extension.)
Host Plant(s) Common Name (Scientific Name)
Willow (Salix spp.)
Insect Description:

The giant willow aphid is medium brown to dark brown with several rows of black patches on the body. This aphid is also covered with numerous fine hairs, which can be seen with magnification and provide a grayish-golden luster to the abdomen. A large dark brown projection is found in the center of the back of the insect. Antennae of the giant willow aphid are less than half the length of the body. Giant willow aphids, as their name implies, are quite large with a body length of 5.0-5.8 mm or just under 1/4 of an inch. This insect may also be referred to as the willow twig aphid. They reproduce using parthenogenesis, or asexual reproduction. No males have ever been found in their populations, and females lay viable eggs. Eggs hatch into nymphs, which are slightly smaller than the adult insects. The life cycle of this aphid is not entirely understood. They may be noticeable by mid-summer and are often most abundant in the late summer or fall. This particular species may be very cold tolerant, and has been observed in the southern portions of its range on host plants into the winter months.
Damage to Host:

The damage caused by this insect is usually minimal, but its size and population numbers may cause alarm. In high populations, most 1 to 3 year old twigs may be covered by these insects. It is primarily a pest of willow or the genus Salix, however reports of this insect on poplar (Populus spp.) exist. Aphids may excrete large amounts of honeydew, or a sugary liquid excrement, which coats the surface of anything beneath the aphids and may promote the growth of black sooty mold. Honeydew is also attractive to stinging insects.
Monitoring:

Search for large aphids on the twigs and small branches of willow. If honeydew is observed on willow, this may be a sign of the presence of this insect.
Cultural Management:

Heavily infested twigs and branches can be pruned and removed if practical, when populations are low. Syringing (or spraying the insects with a strong jet of water from a hose) is also sometimes suggested for aphid management.
Natural Enemies & Biological Control:

Predators and parasites of the giant willow aphid are reportedly rare, perhaps because of their aposematic (warning) coloration. However, the multicolored Asian lady beetle (Harmonia axyridis) has been observed feeding on them (Aphids on World's Plants).
Chemical Management:

Abamectin (NL)

Acephate (NL)

Acetamiprid (L)

Azadirachtin (eggs) (NL)

Beauveria bassiana (NL)

Bifenthrin (NL)

Chlorantraniliprole (NL)

Chlorpyrifos (N)

Chromobacterium subtsugae (NL)

Clothianidin (NL)

Cyantraniliprole (NL)

Cyfluthrin (NL)

Cypermethrin (NL)

Dinotefuran (NL)

Emamectin benzoate (L)

Fenpropathrin (NL)

Flonicamid + cyclaniliprole (N)

Tau-fluvalinate (NL)

Gamma-cyhalothrin (L)

Horticultural oil (L)

Imidacloprid (L)

Insecticidal soap (NL)

Isaria (paecilomyces) fumosoroseus (NL)

Lambda-cyhalothrin (L)

Malathion (L)

Neem oil (NL)

Permethrin (L)

Pymetrozine (NL)

Pyrethrins + piperonyl butoxide (L)

Pyrethrin + sulfur (NL)

Pyriproxyfen (L)

Spinetoram + sulfoxaflor (N)
Notes:

Active ingredients that may be applied systemically include: abamectin (injection), acephate (injection), acetamiprid (injection), azadirachtin (injection, soil drench), chlorantraniliprole (soil drench), clothianidin (soil drench), cyantraniliprole (soil drench, soil injection), dinotefuran (soil drench), emamectin benzoate (injection), imidacloprid (soil drench), and neem oil (soil drench).

Make insecticide applications after bloom to protect pollinators. Applications at times of the day and temperatures when pollinators are less likely to be active can also reduce the risk of impacting their populations.

Note: Beginning July 1, 2022, neonicotinoid insecticides are classified as state restricted use for use on tree and shrub insect pests in Massachusetts. For more information, visit the MA Department of Agricultural Resources Pesticide Program.

Read and follow all label instructions for safety and proper use. If this guide contradicts language on the label, follow the most up-to-date instructions on the product label. Always confirm that the site you wish to treat and the pest you wish to manage are on the label before using any pesticide. Read the full disclaimer. Active ingredients labeled "L" indicate some products containing the active ingredient are labeled for landscape uses on trees or shrubs. Active ingredients labeled "N" indicate some products containing the active ingredient are labeled for use in nurseries. Always confirm allowable uses on product labels. This active ingredient list is based on what was registered for use in Massachusetts at the time of publication. This information changes rapidly and may not be up to date. If you are viewing this information from another state, check with your local Extension Service and State Pesticide Program for local uses and regulations. Active ingredient lists were last updated: September 27, 2024. To check current product registrations in Massachusetts, please visit the MA Department of Agricultural Resources Pesticide Product Registration page and click on "Search Pesticide Products Registered in Massachusetts - Kelly Solutions".