Saturday, August 3, 2013

Pest News for Week of August 5th


From: Steve Frank, Extension Entomologist

Japanese Maple Scale in the Nursery and Landscape

Japanese maple scale, Lopholeucaspis japonica, is active now and much of the summer. It is a small, oystershell-shaped, armored scale introduced to the U.S. from Asia. Japanese maple scale is found in several eastern U.S. states, including Connecticut, Delaware, Georgia, Kentucky, Maryland, North Carolina, New Jersey, Pennsylvania, Rhode Island, Tennessee and Virginia, as well as Washington D.C. Japanese maple scale has a wide host range that in addition to maples (e.g.,  Japanese maples, red maples, paperbark maples and sugar maples), includes Amelanchier, Camellia, Carpinus, Cercis, Cladrastis, Cornus, Cotoneaster, Euonymus, Fraxinus, Gledistia, Ilex, Itea, Ligustrum, Magnolia, Malus, Prunus, Pyracantha, Pyrus, Salix, Stewartia, Styrax, Syringa, Tilia, Ulmus, Zelkova and others.

Although the lifecycle of this pest has not been fully examined, two generations a year are expected in the mid-southern U.S. First generation crawlers emerge in mid-May and the second generation in early August. Management efforts are complicated by the extended crawler emergence that results in first and second generational overlap. Thus, the most recent sample we received had every stage – egg to adult –present at the same time. 

Adult scales and crawlers are very small and most readily observed on bark of dormant deciduous host plants, but can also be found on foliage. The waxy coating on the body of male Japanese maple scales is white and females, eggs, and crawlers are lavender. The most work on this scale has been done by Paula Shrewsbury and Stanton Gill at the University of Maryland. There is also information on Japanese maple scales and other maple pests in our new book:

Oleander Aphids

Anyone who has grown or looked at milkweed has seen oleander aphids. They are orange and usually very abundant. Sometimes oleander aphids become so abundant they reduce plant growth and flowering, but most of the time they are not very harmful. Since they are inevitable you might as well enjoy them. The most enjoyable and interesting thing about these aphids is that you can witness all kinds of ecological interactions. Inspecting a colony of these aphids you will see parasitoids and their mummies; predacious maggots of hoverflies that specialize on aphids; predacious maggots of Aphidoletes midges that bite aphid knees, inject paralytic toxins, then eat the aphids. Many other generalist predators such as green lacewing larvae, lady beetles, and minute pirate bugs also hang around. These are great plants to have in public gardens because you can always teach people about these predators and parasitoids. 

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