My aborvite trees need HELP !!! - Knowledgebase Question

Oakland, Ne
Question by deniseakadia
July 9, 2010
.This is the second year that bagworms infested one of aborvites.This year they made a home next to the tree of the previous year. I sprayed with Seven yesterday. Can you give me some more information. Thank you for your expertise in knowledge and answers to my previous questions.


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Answer from NGA
July 9, 2010

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Bagworms have an interesting lifecycle. They are the larvae of a moth. The female moth cannot fly but their offspring, very small caterpillars, can spin strands of silk and be carried by the wind, an activity called ?ballooning?. Larger larvae may crawl to adjacent plants. That's why you've found them in a nearby tree this year.

Bagworms pass the winter as eggs (300 or more) inside bags that served as cocoons for last year?s females. The eggs hatch in mid- to late May and the tiny larvae crawl out to feed. Each uses silk and bits of plant material to make a small bag that protects and camouflages it as during feeding and growth. Bagworm caterpillars feed for about six weeks, enlarging the bag as they grow and withdrawing into it when disturbed.

The period between hatching and feeding is when they are most vulnerable to insecticides. You can try spraying with Bt (bacillus thuringensis), a botanical that targets caterpillars. It's usually very effective. Others you can try include
Spinosad (Captain Jack?s Deadbug Brew Concentrate, ferti-lome Borer, Bagworm, Leafminer & Tent Caterpillar Spray; Green Light Lawn & Garden Spray Spinosad Concentrate; Conserve, Bonide Caterpillar Killer, or Spectracide Triazicide Once & Done Insect Killer.

Their lifecycle continues until early fall, when the mature larvae attach their bags to twigs and transform into the pupa or resting stage before becoming an adult. Males emerge from their bags in early fall. They search for bags containing immobile females. After mating, the female lays several hundred eggs, leaves the bag and dies. The eggs remain in the bag until they hatch the following May. You can handpick the bags attached to the foliage of your arborvitae this fall and destroy them which will eliminate the next generation.

Best wishes with your arborvitae!

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