Orange-striped oakworms make yearly appearance

This is a quick field note by PhD student Emily Meineke.

For the last few weeks, orange striped oakworms have been raining on my head as I work in the trees. They also drop a lot of

 

 

Large oakworms eat entire leaves except for the mid vein. Photo: EK Meineke

Large oakworms eat entire leaves except for the mid vein. Photo: EK Meineke

poop (entomologists call it frass) which is one of the major complaints by homeowners. Orange-striped oakworms congregate on branches to feed every year in late summer but usually do not cause enough damage to warrant treatment.

Young oak worms cause damage called 'window panning' in which they eat the surface of leaves and feed between tiny veins. Photo: EK Meineke.

Young oak worms cause damage called ‘window panning’ in which they eat the surface of leaves and feed between tiny veins. Photo: EK Meineke.

Young orangestriped oakworms are often light in color and darken as they get older. I have found some parasitized individuals, which means natural enemies are doing their part to reduce oakworm outbreaks. Caterpillars also make great food for birds. We have posted previously about orange-striped oak worm biology and management if you want more information.  

Large caterpillar poops around the base of a tree. Photo: SD Frank

Large caterpillar poops around the base of a tree. Photo: SD Frank

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Sawdust from banded ash clearwing larvae

I just got some great pictures from one of great Extension Agents, Mark Danieley, this week

Sawdust accumulated around the base of an infested ash tree. Photo: Mark Danieley

Sawdust accumulated around the base of an infested ash tree. Photo: Mark Danieley

of some pretty messed up ash trees in a parking lot. They have sawdust (frass) accumulated on the ground around their trunks and in clumps on the bark. Of course the first thought was whether the tree was infested with emerald ash borer. Mark noted however that the holes were round not D-shaped. Turns out the trees are infested with banded ash clearwing larvae. As the larvae feed they periodically shove frass  out of their galleries to keep them clear. This time of year the larvae are getting very big and thus feeding heavily. Adults will emerge soon. Thus, the holes in the pictures are from last year when adults emerged front he same trees. That is why they did not have characteristic pupal casings sticking out of the holes.

Sawdust in clumps and round exit holes on tree bark. Photo: Mark Danieley

Sawdust in clumps and round exit holes on tree bark. Photo: Mark Danieley

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.