BTA (Mindarus abietinus)

PDF version of BTA - Facts at a Glance (including photos)

Where from: Native to US and to NC

Host plants: All true firs

Symptoms: Needle curl - the tree may grow out of from spring until fall; sooty mold

Life cycle:

• How overwinters - as eggs on shoots, primarily of most current growth
• Eggs hatch in March over 3 week period
• Only one generation/year with different forms, each requiring four molts to maturity. The stem mother hatches from the egg and produces live young (all are female). The second form is a winged aphid and produces live young. The last form includes males and females that mate to produce eggs.
• Eggs are lain in June

Weather considerations: The BTA is only a problem some years. Warm springs favor aphid hatching and reproduction. Cool weather at budbreak delays tree growth and maturation as well as predators, often resulting in more needle curl. Wet weather allows needles to grow out of tight curl.Important cultural practices:

• Don't interplant
• Avoid excess nitrogen
• Maintain flowering ground covers
• Clear cut fields in 1-2 years

Scouting: You can’t predict aphid severity by the amount of damage the previous year. Scout for BTA eggs on shoots from July through February for an indication of potential damage. Examine developing cones for aphids in spring. Take foliage beats once all the twig aphids have hatched in April. Take into account predators.Biological control:

• Hover fly larva
• Lady beetle adults and larva
• Lacewing larva

Control considerations:

• Start treating fields the year before harvest - don't treat younger trees
• Remove cones before treating
• Rotate chemicals from year to year
• Retreating if treatment fails seldom works