Forest Snapshot November 2025

Important Dates

Join the Penn State Extension Forestry and Wildlife Team at the 110th Pennsylvania Farm Show as part of the PA Hardwoods Exhibit. The 2026 event will take place from Saturday, January 10, to Saturday, January 17, at the Pennsylvania Farm Show Complex and Expo Center in Harrisburg. 

Save the date for the 2026 Forest Health, Insect, and Disease Briefing on March 3, 2026. Registration will open shortly.

Forest Health

Monitoring for HWA Predator Beetles on Your Property 

Laricobius nigrinus and Laricobius osakensis are both winter predators of hemlock woolly adelgid that have been introduced extensively throughout Pennsylvania and other surrounding states. While a number of predator insects have been released to control HWA, and more are currently being evaluated, these two species of Laricobius show particular promise. Unlike most predator beetles of HWA, Laricobius is a winter feeder. Both the adult and the larvae feed on HWA from November to May. The adults consume adelgids before laying their eggs singly in HWA egg sacs. Each Laricobius larva consumes HWA eggs or crawlers before it pupates in late spring. Laricobius beetles have become increasingly easy to recover and are now being found many miles from their original release sites. These predators are clearly reproducing and redistributing themselves throughout the landscape, evidence that they are becoming established. It is likely that Laricobius beetles are present on many private lands throughout eastern and southern PA. 

The following instructions are intended to help homeowners and land managers determine whether these beneficial insects are present on their HWA-infested hemlock trees. All monitoring must take place on your own private lands.

You are more likely to recover Laricobius in an area that has numerous hemlocks heavily infested with HWA. Hedge rows and forest edges are excellent places to look for them. Target HWA-infested branches in open areas that receive direct sunlight. If no living HWA is present on a branch, there is nothing for Laricobius to feed on, and they will not be present.

The best time to monitor for Laricobius is November through April. November-February, you are more likely to find adult beetles; March-April, you are more likely to find larvae. As spring progresses, beetle larvae will drop down into the duff layer to pupate. It is extremely unlikely that you will locate Laricobius during the summer months. Search for beetles on warmer sunny days. Do not attempt to monitor under adverse weather conditions (e.g., heavy wind, rain, or temperatures below freezing). Sunny days with temperatures above 45°F, between 10 am and 4 pm, are the best times to recover beetles. 

Gather equipment: a long pole to tap/"beat" hemlock branches, and a "beat sheet" (large, light-colored fabric with rigidity, such as a canvas sheet on a wooden frame) are essential. Optional items are a hand lens (with a light is nice) to help in identifying beetles, and a thumb counter to record the number found. Also optional are a small paintbrush to assist in beetle collection, and a small vial filled with alcohol to preserve any specimens collected. 

Visually examine the HWA ovisacs before beating to look for signs of disturbance. Ovisacs that have been visited by beetles may appear torn open or teased apart. Undisturbed ovisacs will look more like round cotton balls. While this is not a guarantee that beetles are present, it is a sign that further monitoring and observation may prove fruitful. 

Put the beat sheet under the branch to catch any falling beetles. Most beetles will dislodge easily from trees, so avoid brushing or otherwise disturbing the branches of the trees to be sampled until the beat sheet is in position to collect falling beetles. Tap the branch smartly with the stick 5-10 times above the beat sheet, keeping the sheet directly under the branch. You should tap hard enough to dislodge beetles, but not so hard that the branch bounces away from the sheet. Scan the beat sheet for Laricobius, remembering to look on/under leaves, twigs, and needles for beetles hiding in the debris. Record the number of beetles found in the sheet (a thumb counter can be helpful to keep track across multiple branches/sheets). If desired, carefully collect a beetle with a small paintbrush and put it in a vial of alcohol for species confirmation. After counting, recording, and sampling insects on your beat sheet, gently dump the remaining insects and debris at the base of the tree so that beetles can return to their prior location on the tree. 

If you do not find any Laricobius after the first try, try again on another day. It can take substantial effort and several attempts to recover any. 

Studies are currently underway to measure the level of predation of Laricobius on HWA. It is still unknown how many beetles are “enough” to protect a tree or a stand of trees from HWA damage. Currently, chemical treatment remains the only known method to protect an individual tree from HWA and halt its decline. 

Contact the Bureau of Forestry, Forest Health Division for further support and sample identification: PaForester@pa.gov or 717-783-2066 

Invasive Species 

As the winter season approaches, you may be thinking of putting away the vegetation management tools and herbicides. Not so fast! There’s plenty of work to be done during the non-growing season that will help you continue to advance your plant control goals. Grab your loppers or a saw and get to work cutting down those nasty invasive shrubs or trees (except tree-of-heaven or Japanese angelica tree). 

Hunt down woody invasive vines, like oriental bittersweet, Japanese honeysuckle, English ivy, etc., that are climbing trees or structures and cut them (once close to the ground and again several feet up to create a gap between the hanging vine and the stump). Foliar herbicide can be applied to the resprouts next summer. 

Grab a shovel or a sprayer and neutralize rosettes of weedy winter annuals, like yellow rocket, or biennials, including garlic mustard, teasel, poison hemlock, etc. They will be green all winter long and easy to spot among the dormant vegetation. Dig out the rosette or sever the root collar, or spray them with systemic herbicide anytime the temperature is above freezing.

Take advantage of the cooler, non-buggy weather and don't give those invasives a reprieve! You can enjoy a hard-earned cup of hot cocoa when you’re done. 

Native Species 

Winterberry (Ilex verticillata), also known as common winterberry and winterberry holly, is a deciduous shrub in the holly family (Aquifoliaceae). Winterberry is found on moist, acidic sites across Pennsylvania. The specific epithet, verticillata, means "having parts in whorls" in reference to the appearance of the berries encircling the stems. As winter approaches, the bright red berries, which give this plant its name, will stand out against snowy landscapes, providing aesthetic interest for home gardens and serving as food sources for wildlife. Winterberry plants produce either male or female flowers, and both are necessary for cross-pollination and fruit set. Consider planting a grove of winterberry with 1 male plant for every 10 female plants. Male plants must be within 50 feet of female plants to promote pollination.  

Winter stems of winterberry are commonly used in woody cut floral arrangements. Keep an eye out for the bright red fruits often seen in winter planter boxes outside of businesses in your community this season. 

Wildlife and Insects

As mating begins, the calls of great horned owls become more frequent. Males hoot back and forth territorially. Pairs of great horned owls begin breeding as early as mid-December. Northern songbirds like pine siskins, red-breasted nuthatches, common redpolls, and white-winged and red crossbills may come south if the pine crop is small in their usual Canadian habitat. Pine siskins, nuthatches, and redpolls are visitors to bird feeders in those years.