Japanese maple scale

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 CT, DE, GA, KY, MD, NC, NJ, PA, RI, TN and VA, 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.

Brian Kunkel, University of Delaware, Bugwood.org

Brian Kunkel, University of Delaware, Bugwood.org

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  but there may be more. 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 JMS and other maple pests in our new book here: http://ecoipm.com/extension/extension-resources/

A link to the UMD fact sheet is here: http://ipmnet.umd.edu/nursery/docs/JapaneseMapleScale-UMD2011.pdf

 

Maple spider mites

Maple spider mites (Oligonychus aceris) are common and damaging pests of maple trees throughout the Eastern United States. These spider mites overwinter on the trunk and

Adult maple spider mite. Photo: AG Dale

Adult maple spider mite. Photo: AG Dale

branches of maple trees and migrate to the underside of leaves in the spring. Once there, they use their mouthparts to pierce leaf cells and feed on cell sap. This causes fine flecking called stippling and eventually leaves turn gray or brown after heavy feeding. Maple spider mites have multiple generations per year which enables them to become quite abundant during a single season. These pests are a more serious problem in nurseries due to the close proximity of potted trees and applications of broad spectrum insecticides like permethrin. For example, our research has shown that applications of permethrin targeting ambrosia beetles can wipe out natural enemies and result in secondary maple spider mite outbreaks. Maple spider mites can also be abundant on landscape trees. Trees in parking lots and along roads are most likely to be infested.

Maple spider mite egg attached to tree bark. Photo: AG Dale

Maple spider mite egg attached to tree bark. Photo: AG Dale

A hand lens or stereo microscope is necessary for correct identification of these mites but damage is a good indicator of infestation. They are dark brown or red with hairs along their backs and have eight legs while some immature forms exhibit green coloration and have six legs. Red eggs of these mites can be found on tree limbs and yellow or clear eggs can be found on leaf surfaces. Treatment for these pests includes foliar applications of acaricides. Maple cultivars differ in susceptibility to maple spider mites and other maple pests like leafhoppers. A chapter in a recent free ibook IPM for Select Deciduous Trees in Southern Nursery Production describes more

Maple spider mite damage. Photo: AG Dale

Maple spider mite damage. Photo: AG Dale

about management of maple pests and other tree pests. A recent article in Nursery Management and a fact sheet describes mite biology and management. This time of year trees may not be sold until fall so the condition of leaves is not as much of an issue. On landscape trees mite damage reduces fall color and summer color because leaves are gray, yellow, or brown instead of green.

 

Brown branches on arborvitae

This time of year arborvitae plants may get a little shabby. Many branches get short brown

Damaged tip from arborvitae leaf miner. Photo: SD Frank

Damaged tip from arborvitae leaf miner. Photo: SD Frank

tips. Other branches may turn brown and just hang on the plant. Arborvitae leaf miners, Argyresthia spp., are tiny moths responsible for brown tips. Moths lay eggs on new growth which is why the tips of plants are damaged. Larvae burrow into leaf scales and mine foliage as they feed and develop.

Larvae overwinter in the mines and resume feeding in spring. Damage is most evident in winter and early spring so the damage you see now is likely from mines initiated last year. Mines can be differentiated from other damage by looking for exit holes and by opening damaged tips to look for larvae.

If you have larger brown branches that are hanging, barely attached to the tree, you

Flagging branch from bark beetle feeding. Photo: SD Frank

Flagging branch from bark beetle feeding. Photo: SD Frank

probably have damage from Phloeosinus spp. bark beetles. Commonly called cypress bark beetles, eastern species attack arborvitae. These beetles chew branches 15-30 cm from the tip making a groove or short tunnel that weakens the branch. The branch then breaks easily in the wind and turns brown, a condition called flagging. You can look for the hollowed end of branches you suspect were damaged by these beetles.

Mimosa webworm

Mimosa webworms are active in Raleigh. I saw initial webbing just a week or so ago but

Small web in a mimosa tree. Photo: SD Frank

Small web in a mimosa tree. Photo: SD Frank

now they are in full swing. These are annual pests of mimosa trees which many people consider pests in their own right. However, if you are you of the many folks who love mimosa trees sans messy caterpillar webbing then it is time for action. The best way to prevent heavy infestations and extensive webbing is to prune out the nest when they are small. Moths overwinter as pupae attached to tree trunks, buildings, or other sheltered locations. The adults emerge in June or so to lay eggs on mimosa and honey locust trees. Caterpillars feed within the webbing for several weeks before pupating. There are multiple generations per year. Most insecticides available for caterpillar control will also control

Mimosa webworm. Photo: SD Frank

Mimosa webworm. Photo: SD Frank

mimosa webworm but remember that contact is difficult since they live in waterproof webs. In most cases mimosa webworms will not reduce the health or growth of their rapidly growing hosts. They also don’t seem to eat all the seedlings that pop up all over my yard from the tree next door. http://www.ces.ncsu.edu/depts/ent/notes/O&T/shrubs/note07/note07.html

Protect these soft scale predators

Hyperaspis binotata is an important natural enemy of soft scales in eastern US. It

Hyperaspis binotata adults from Simanton, 1916.

Hyperaspis binotata adults from Simanton, 1916.

particularly came to the attention of researchers trying to control terrapin scale on orchard trees in the early 20th century. It feeds on lecanium scales, Pulvinaria scales such as cottony maple leaf scale, tuliptree scale, terrapin scale, and others. There are many other lady beetles that feed on scale insects. Hyperaspis is a large genus of small lady beetles that feed on scale insects, aphids, and mealybugs.

They typically are black with red or yellow markings. They can be difficult to distinguish from each other. A similar species is the twice stabbed lady beetle, Chilocorus stigma, which is common around scale infestations but larger than Hyperaspsis species.

The larvae are covered in white wax making them look something like mealybugs. I found some feeding

IMG_0774

Hyperaspis larvae on tuliptree scale. Photo: SD Frank.

on tuliptree scale in Asheville last year. Its important to recognize these so you don’t think you have a double infestation of scales and mealybugs. Its easy to tell the difference since they move much faster than mealybugs (meaning that they actually move).

Hyperaspis binotata occurs throughout eastern North America. Beetles overwinter at the base of infested trees and leaf litter. They emerge from hibernation in early spring around the time many of its prey also resume feeding and development. Eggs are deposited singly near scales. The H. binotata life cycle requires about 39 days to complete.

Twice-stabbed lady beetle on a red maple covered in gloomy scales. Photo: SD Frank.

Twice-stabbed lady beetle on a red maple covered in gloomy scales. Photo: SD Frank.

A single Hyperaspis larvae may consume up to 3000 terrapin scale nymphs to complete development. They are probably critical to regulating scale insect abundance in natural habitats. We are not sure how well they perform this service in urban areas. Hyperaspis spp. and other natural enemies are killed by many insecticides. Protecting natural enemies can be critical to reducing urban scale insect outbreaks as seen during wide-spread spray campaigns to control nuisance flies or landscape pests.

Hyperaspis binotata larvae from Simanton, 1916.

Hyperaspis binotata larvae from Simanton, 1916.

More information and pictures are on Dr. Mike Raupp’s ‘Bug of the Week’ website: http://bugoftheweek.com/blog/2013/1/7/waxy-ladies-hyperaspis-lady-bugs and in the publication by from which I copied the pictures above.

Simanton, F.L. 1916. Hyperaspis binotata, a predatory enemy of the terrapin scale. Journal of Agricultural Research, vol. VI, no. 5, pp. 197-204.

 

Leaf cutter bee damage and conservation

I have gotten several phone calls about leaf notches on redbud trees. This characteristic damage is caused by leaf cutter bees in the genus Megachile. Leafcutters in Megachile

Leafcutter bee. Photograph by Sam Droege, USGS

Leafcutter bee. Photograph by Sam Droege, USGS

and other genera are solitary bees that nest in hollow grass stems or other pithy stems they can easily excavate.  They will also make nests in existing holes in wood but do not bore their own holes in wood (those are carpenter bees). Adult leaf cutter bees can be about as big as honey bees. They cut out round pieces of leaves to line their nests and pack in between brood cells. Damage by leaf cutter bees is general insignificant. In this area they seen to prefer

Leaf notches cut by leafcutter bees on a redbud tree. Photo: S.D. Frank

Leaf notches cut by leafcutter bees on a redbud tree. Photo: S.D. Frank

redbuds but will cut other plants including maples and roses. I have never seen more than a few leaves damaged on any particular tree and the damage is not enough to affect tree growth or health. Leafcutter bees are important pollinators of many native plant species and fruit and vegetable crops. In many urban and rural areas the plant species bees use for nesting have become less common than they used to be. Thus, bees cannot find suitable reedy grasses of tree holes to nest in. You can help conserve leaf cutters and other bees species by creating nest tubes.  These are fairly simple contraptions that just require tying together bundles of reeds or drilling holes in blocks of wood to replace the nest substrate that used to be provided by plants. Visit April Hamblin’s other recent blog post for details. April is conducting research on how urbanization and urban warming affect bee communities, individual survival, and nesting. Visit her guest blog on yourwildlife.com or project description for details of her work.

Leafcutter bee nest with cells divided by rolled up leaves. Each cell holds a pollen ball and one egg to develop into an adult bee one day. These bees are also solitary. Photograph by Joel Gardner, Wild Bees and Building Homes.

Leafcutter bee nest with cells divided by rolled up leaves. Each cell holds a pollen ball and one egg to develop into an adult bee one day. These bees are also solitary.
Photograph by Joel Gardner, Wild Bees and Building Homes.

Overall leafcutter bees are far more beneficial than harmful (they also rarely sting unless handled). My suggestion is to tolerate the subtle damage these bees cause and use it to teach other people about bees.  If you are growing plants for sale you may not be able to do this but I rarely see leaf cutting on nursery stock.

MS student April Hamblin contributed to this post.

Imported willow leaf beetle

Imported willow leaf beetle (Plagiodera versicolor) adults are metallic blue. This time of

Imported willow leaf beetle. Photo: SD Frank

Imported willow leaf beetle. Photo: SD Frank

year adults and larvae are feeding on willows. The adult beetles overwinter outdoors under bark or in leaf litter. They and emerge from hibernation sites in spring around the time willows start getting leaves since adults prefer new leaves. Females lay pale yellow eggs that hatch into voracious larvae. Adults and larvae skeletonize leaves which can give trees a brown cast as damaged leaves crisp in the sun. In some cases though they can eventually defoliate trees like the one I saw walking to work today. Insecticides labeled for leaf feeding beetles such as spinosad, imidacloprid, and chlorantraniliprole can be used if needed. Unfortunately, these beetles are here to stay so efforts to prevent any

Imported willow leaf beetle eggs. Photo: SD Frank

Imported willow leaf beetle eggs. Photo: SD Frank

damage to willows is in vain. High populations that cause complete defoliation pose a risk to tree health and may warrant management. Otherwise some damage is inevitable so go out and look at the beautiful beetles.