Saturday, April 27, 2013

Pest Alert for Week of April 28th


From: Steve Frank, Extension Entomologist

Ambrosia Beetles Still Active

Just a quick update in case you are not trapping ambrosia beetles. We are still finding a lot of beetles in traps. This week we had 132 attacks on one tree in our experimental nursery. Management of ambrosia beetle ( damage requires pyrethroid applications every 3 weeks to the trunks of trees. Ambrosia beetles usually attack below the first scaffold branches so you do not need to spray the canopy. Most folks apply permethrin with an airblast sprayer. We have tested a manual sprayer and fold more complete, even coverage. You can read about it in a recent paper ( The manual sprayer has two opposing nozzles to quickly cover tree trunk with insecticide. It takes a little longer but uses less insecticide and reduces drift and secondary mite outbreaks.

It’s Still Aphid Season . . .

Last week I reported on rose aphids covering the buds of a rose vine in my neighborhood. This week I poked around campus and found several more aphid species. The first site was spirea aphids. These aphids were coving the new tips of spirea plants at a park in Cary, North Carolina. The result is distorted foliage if they feed on the growing tips too long.

Last week I found some crape myrtle aphid eggs on a tree that still had leaf buds but no leaves. They were shiny black and tucked beneath slivers of papery bark. This week when I went back to find them I only found shriveled black shells. Several days later I found the first crape myrtle aphids of the year. This coincided with the first full grown leaves. Crape myrtle aphids are specialists and only feed on crape myrtle. They occasionally become abundant but are usually subdued by natural enemies.

Finally I found tulip poplar aphids starting to build up on tulip poplar leaves. I watch these every year. For a couple weeks the aphid density increases then you start to see parasitoid mummies and lady bug eggs. For the rest of the summer they stay under control.

Aphids often become abundant this time of year because they are slightly ahead of their predators and parasitoids. However, soon the natural enemies catch up and keep the aphid populations in check. In many cases having some aphids on the plants around your house is good because it attracts predators and parasitoids that will feed on other more damaging pests.

Protecting Pollinators

This time of year many folks are applying systemic neonicotinoid insecticides to their plants and grass. Research has found that these insecticides move into plant nectar and pollen. Through this route they can negatively affect pollinators and especially bees. I reposted a blog post about protecting pollinators from last year ( This provides more detail and links to a review by the Xerces Society about the effect of neonics on pollinators.

Boxwood Leaf Miners Emerging

Last week I saw a lone boxwood leaf miner adult hovering around a bush on campus. This week I went to look for more. I didn't find adults the day I went out but did find pupal casings sticking out of leaves. This indicates adults recently emerged. The maggots pupate in the leaf blister. As the adult emerges the pupal case get caught on the leaf. This holds the leaf in place so the adult can wriggle out. Boxwoods can be treated with a pyrethroid to prevent flies from landing on the bush to lay eggs but watch out for mite outbreaks. Imidacloprid will kill maggots within the leaves but (based on article above) it is best to apply after flowering.

Recommendations for the use of chemicals are included in this publication as a convenience to the reader. The use of brand names and any mention or listing of commercial products or services in this publication does not imply endorsement by North Carolina State University, North Carolina A&T State University or North Carolina Cooperative Extension nor discrimination against similar products or services not mentioned. Individuals who use chemicals are responsible for ensuring that the intended use complies with current regulations and conforms to the product label. Be sure to obtain current information about usage regulations and examine a current product label before applying any chemical. For assistance, contact an agent of North Carolina Cooperative Extension.

For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.