Yellow Jackets in the Landscape

Yellow jackets are social wasps and are well equipped to defend a nest when disturbed. They almost always nest in the ground. They really don't dig, so they depend on preexisting holes or loose organic matter that they can remove. In the landscape, container-planted material where the peat moss has decomposed, mulch piles, voids under sidewalks and rotting landscape timbers, and even places where stumps or logs were buried in the yard during new home construction are common locations. The rarely seen nests are quite similar to the paper hornet nests that are sometimes seen in trees, but on a smaller scale.

Yellow jackets can actually be considered beneficial because they eat a lot of other insects. They may even help indicate scale infestations if they are seen scouting plants for honeydew. However, a nest in the wrong place may need to be treated. The best control is usually an aerosol can of "hornet and wasp killer" sprayed directly into the hole in late evening. The product must be delivered inside the nest or it will not be effective. While pouring gasoline down the hole is tried and true, it is illegal, dangerous, and will ruin the soil making it hard to grow anything in that spot for a while. Nest populations start from a single queen every spring and build through July. When enough individuals are present, a disturbed nest will respond in defense. For more information, see Residential, Structural and Community Pests Insect Note No. 15 at http://www.ces.ncsu.edu/depts/ent/notes/Urban/horn-yj.htm.

From: Steve Bambara, Extension Entomologist

Japanese Beetles Have Arrived

On Wednesday, June 16, we caught the first Japanese beetles of the year on the North Carolina State University campus in Raleigh. Last year Japanese beetles were not very abundant here so it will be interesting to see what this year brings. As most people know, Japanese beetles emerge once per year to feast on a variety of ornamental and crop plants. Their favorite ornamental hosts include roses, rosaceous trees and shrubs such as crab apple, crape myrtle, and linden. Beetles aggregate on plants in response to plant volatiles (smells) and pheromones from other beetles. This aggregation can result in rapid defoliation of trees and shrubs. It also means that one plant can be severely damaged while nearby plants are just nibbled on.

Japanese beetle traps do not offer any protection to landscape plants and may actually attract more beetles on to your property, so hang them in your neighbor’s yard! Likewise, treating a lawn for Japanese beetles grubs will not reduce defoliation of plants on that property since beetles fly in from great distances. Long-term protection for landscape and nursery plants can be achieved a neonicotinoid insecticide such as imidacloprid (e.g., Merit, Marathon II) or acetamiprid (Tri-Star). A new product with extremely low vertebrate toxicity but good efficacy for a number of pests including Japanese beetles is Acelepryn (chlorantraniliprole). For more information on the biology and management of adult Japanese beetles in nurseries and landscapes, consult Ornamentals and Turf Insect Information Note No. 147 at http://www.ces.ncsu.edu/depts/ent/notes/O&T/flowers/note147/note147.html.

From: Steve Frank, Extension Entomologist