Important Dates

Save the date! The PA Timber Show will be held at Ag Progress Days on June 6th and 7th.

Forest Health

Early instar Spongy Moth caterpillars prefer to feed on oaks. Suppression of these non-native populations is best conducted when larvae are small and more susceptible to appropriate insecticides, and before larger instar caterpillars can do more damage. Photo credit: Sarah Johnson

Spongy moth caterpillars (Lymantria dispar) are destructive, invasive pests found across Pennsylvania and become active in our forests in the spring. Newly hatched caterpillars are small, up to ¼ inches in length, and hairy. Older caterpillars, 1.5 to 2.5 inches in length, are yellow to gray in color with tufts of bristle-like hairs and five pairs of blue dots followed by six pairs of red dots along their backs. As caterpillars, the spongy moth has been found to feed on the leaves of over 300 species of trees and shrubs with preference for oaks. Dense spongy moth infestations can cause mass defoliation resulting in forests with barren, wintry appearance in the summer. Trees can develop another set of leaves in the summer but if trees experience defoliation over multiple seasons, it can lead to tree death.

Later in the summer, adult spongy moths will emerge, living for a few days to mate. Females will each lay a single egg mass containing 200-1,000 eggs. Egg masses are usually found on tree trunks and branches but can also be laid on many outdoor items including firewood, lawn furniture, and under bumpers of vehicles and campers. The spongy, tan egg masses give this moth its common name.

Fall cankerworm caterpillars — Fall cankerworm is a native species that will feed on many hardwood tree species. Populations can reach outbreak proportions locally, and though they often collapse within 1 to 2 years, the damage they cause can lead to tree mortality when combined with other stressors such as drought, poor site conditions, and other biotic and abiotic factors. Caterpillars can be light green, or a combination of light green and dark gray when populations are high. Photo credit: Sarah Johnson

Fall cankerworm (Alsophila pometaria) is a native pest of hardwood trees in North America. This insect gets its common name from the adults that are active in the fall. The larvae, commonly called inchworms, loopers, or measuringworms, feed on leaves in the spring. Each year, the fall cankerworm causes small areas of defoliation across Pennsylvania that can lead to tree mortality when combined with environmental stressors. Mature larvae are around 1-inch long, with light green to dark gray in color.

Adult fall cankerworm moths emerge from cocoons spun with silk and soil particles that lie just below the surface of the forest floor, after the freezing temperatures in late October to early December. The moths will live for a short time to reproduce. Females will lay about 100 eggs in compact rows in a single layer on twigs and branches.

plane flying over a forest doing an aerial application of insecticides — Aerial suppression is conducted with fixed wing or rotary aircraft. These aircraft uniformly apply Lepidopteran-specific insecticides to designated spray blocks. Effective insecticides are *Bacillus thuringiensis* kurstaki, a naturally-occurring bacterium, or Tebufenozide, a chemically-derived active ingredient that is more appropriate when caterpillar populations are very high. Photo credit: Sean Freidhof, monitoring a spray block

In some cases, aerial applications of Lepidopteran-specific insecticide, which targets moths and butterfly species, are used to suppress populations of spongy moth and fall cankerworm in their larval stages. These applications are sprayed on designated forest blocks using fixed wing or rotary aircrafts. The Department of Conservation and Natural Resources (DCNR) and the PA Game Commission routinely use aerial spraying on their lands and certified aerial contractors can be hired to spray private lands. Contracts should be arranged prior to the spring to ensure spraying during early larval stages.

Invasive Species

White cluster of flowers of the invasive multiflora rosa (top) compared to singular, pink flowers of the native pasture rose (bottom). Photo credit: Emily Rojik

Early June is normally the time when multiflora rose becomes noticeable due to its abundant flower clusters in bloom. During flowering, multiflora is easy to identify because it produces small white flowers that grow in clusters (hence the name 'multiflora'). All of our native roses will have pink flowers that are larger and mostly singular. Non-invasive ornamental roses may have white flowers, but they also tend to be larger and single.

The fringed stipule of multiflora rose (top) compared to the smooth stipules of pasture rose (bottom). Photo credit: Emily Rojik

Another characteristic feature to distinguish multiflora rose from native roses is fringed stipules. Look closely at the leaf petiole (or the leaf stalk, where it attaches to the woody stem). Stipules are ‘wings’ of green leafy tissue that line the petiole. Not all plants have stipules, but most roses do, and multiflora rose is unique in having stipules that are finely divided and look sort of hairy or fringy. (Some species/varieties of ornamental roses may also have fringed stipules, but most do not). Native wild roses will always have smooth, non-fringed stipules.

For more details on multiflora rose identification and control, visit Extensions resources:

Multiflora rose accurate identification

Multiflora rose

Native Species

blackberry fruit — A cluster of black raspberry fruits. The ripe, black fruit is surrounded by unripe fruits ranging in color from white to red. Photo credit: Cathryn Pugh

The summer in Pennsylvania is the prime time to black raspberries (Rubus occidentalis). The multi-stemmed shrubs form dense colonies with long, arching canes, often growing along forest edges and disturbed sites. The round stems will be purplish red in color with a waxy coating and covered in prickles. The clusters of unripe, pale pink fruits will ripen black and will easily pull off the plant when they are ready for harvest. Thickets of black raspberry provide shelter for wildlife, the flowers are important nectar sources for pollinators, and the fruits are high value food sources for many species of songbirds, game birds, and small and large animals- including humans! Fruits can be eaten fresh, used in baked goods, jams, and jellies.

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