Mindarus abietinus

Balsam twig aphids and damage. Photo: E. Bradford Walker, Vermont Department of Forests, Bugwood.org.
Scientific Name: Mindarus abietinus
Common Name: Balsam Twig Aphid
Growing Degree Days (GDD's): 30–120, Base 50F, March 1st Start Date (Source: Robert Childs, UMass Extension.)
Host Plant(s) Common Name (Scientific Name)
Alpine Fir (Abies lasiocarpha) *Preferred host.
Balsam Fir (Abies balsamea) *Preferred host.
Colorado Spruce (Picea pungens)
Fraser Fir (Abies fraseri) *Preferred host.
Grand Fir (Abies grandis) *Preferred host.
Juniper (Juniperus spp.)
Siberian Fir (Abies sibirica) *Preferred host.
White Fir (Abies concolor) *Preferred host.
White Spruce (Picea glauca)
Insect Description:

Eggs overwinter in the cracks and crevices of host plant bark on the trunk and branches. Eggs are brown in color and covered in white waxy rod-like structures. Eggs hatch approximately in April and May and become nymphs that mature quickly into "stem mothers" which are wingless and can each produce 20-40 living young without laying eggs. These new young feed on buds and tender needles, making them an early-season pest and causing the most damage at that time. This generation will mature into a winged adult form capable of dispersing to other trees and mating. These aphids can feed, but in this later stage they are much less damaging to the plants than those born of the stem mothers. This generation will lay brown eggs and cover them with white, waxy material onto the bark cracks and crevices which will overwinter for the next season. Several generations can occur per year. 
Damage to Host:

Damage by this pest usually not noticed until pest has gone. This is a very early season pest and damage may stay on host into the next growing season. Creates much honeydew and distorts foliage (twisted needles). Honeydew can stick needles together in heavy populations. Some needle death may occur. Pest active at bud break. This insect may be a significant aesthetic issue in Christmas trees.
Monitoring:

Look for the curled or stunted needles from previous season's damage from roughly July through March. If damage is noted, scan bark for white-covered eggs. When monitoring aphid activity in the early spring (April), scout trees likely to break bud the soonest, as those may become infested first.
Cultural Management:

Avoid applying nitrogen fertilizer in the spring as this has been observed to increase aphid numbers.
Natural Enemies & Biological Control:

Choose chemical management options (if necessary) that are least detrimental to beneficial insects that act as natural enemies. Many insects will prey on these aphids, including but not limited to adult and larval lady beetles, lacewings, and the larvae of syrphid/flower/hover flies.
Chemical Management:

Abamectin (NL)

Acephate (NL)

Acetamiprid (L)

Azadirachtin (eggs) (NL)

Beauveria bassiana (NL)

Bifenthrin (NL)

Carbaryl (L)

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)

Pyrethrins+piperonyl butoxide (L)

Pyrethrin+sulfur (NL)

Pymetrozine (NL)

Pyriproxyfen (eggs and immatures) (L)

Spinetoram+sulfoxaflor (N)

Tau-Fluvalinate (NL)
Notes:

Spray on warm days. Oil sprays may not reach all aphids hidden in curled needles.

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".