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Longistigma caryae

Giant bark aphids. Photo: Jim Baker, North Carolina State University, Bugwood.
Scientific Name: 
Longistigma caryae
Common Name: 
Giant Bark Aphid
Growing Degree Days (GDD's): 
Not available at this time.
Host Plant(s) Common Name (Scientific Name): 
Beech (Fagus spp.)
Birch (Betula spp.)
Chestnut (Castanea spp.)
Hickory (Carya spp.)
Linden (Tilia spp.)
Northern red oak (Quercus rubra)
Oak (Quercus spp.)
Pecan (Carya spp.)
Pin oak (Quercus palustris)
Sycamore (Platanus spp.)
Walnut (Juglans spp.)
Willow (Salix spp.)
Insect Description: 

Giant bark aphids, as implied by their common name, are large. They reach up to 6 mm. in length, or just under 1/4 inch. Their long legs make them appear even larger. This species has short, black cornicles (two projections on either side of the end of the abdomen). Eggs are laid by the females late in the growing season, possibly into the fall, and overwinter. Eggs are elongated in their shape and orange-brown when freshly laid but eventually change in color to a shiny black. They may be found in cracks and crevices of the bark or smooth bark on smaller branches. These insects are often noted as active throughout much of the growing season, but historically become the most numerous by the late summer. These particular aphids, when present in large numbers, can cause noticeable damage to their hosts. When populations are high, twigs may be completely covered in their eggs. Occasional outbreaks of this insect have been recorded in the history of the US, such as in 1882 when they were found on sycamores over a large part of the United States (Weed, C.M. 1891).

Damage to Host: 

May cause noticeable injury to the host by killing twigs and branches, particularly when populations are high, due to heavy feeding. Heavy populations are most noticeable by late summer. Giant bark aphids may also excrete large amounts of sugar-rich honeydew (liquid excrement) that can coat surfaces, including leaves, beneath where they are feeding. Honeydew then promotes the growth of black sooty mold and may also be attractive to stinging insects.


Scout the trunk, branches, and twigs on susceptible hosts for feeding aphids or overwintering eggs.

Cultural Management: 

Heavily infested twigs and branches can be pruned and removed if practical. 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: 

Parasitic wasps, lady beetles, syrphid fly maggots, lace wings, and other predaceous insects feed on aphids, including the giant bark aphid, and often keep populations below damaging levels. If chemical management is occasionally deemed necessary to protect high-value plants when giant bark aphid populations are high, select options that pose the least risk to these natural enemies and beneficial insects. Preserving natural enemies is an effective form of management.

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)

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)

Tau-fluvalinate (NL)


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: January 2024. To check current product registrations in Massachusetts, please visit: .