Southern Pine Beetle and other insects
Hello,
It's been a while since I wrote a journal post, so I thought I'd deliver an update on the southern pine beetle and its effects on the serpentine barrens. The southern pine beetle (Dendroctonus frontalis) is a southern US native that is a generalist feeder on pine trees. Historically reported as far north as southern Pennsylvania and the New Jersey Pine Barrens, it has, within the past decade or so, crept up the New England littoral as far as Massachusetts.
In healthy pine forests, D. frontalis can maintain an endemic presence, where low numbers of beetles prey on stressed or damaged trees. However, periodic epidemics occur, usually when large numbers of stressed and weakened pines have allowed a beetle population boom. A healthy pine can fight off the pine beetles by exuding resin, flushing the beetles out of the bark. However, in the face of large numbers of pine beetles, an individual pine tree will run out of resin and be unable to expel all of the beetles. During epidemics, large numbers of healthy pines can be wiped out as the beetles dig galleries in the bark and introduce blue-stain fungus, ultimately blocking the vascular tissue and girdling the tree. Adults typically disperse during the spring, flying up to 2 miles from the host tree (although they only survive for a few days), while infestation progresses in the summer. Secondary dispersal can occur during the fall; winter is a period of quiescence, and exceptionally cold winters (for this area) may cause beetle mortality.
Unfortunately, the thick, closely-spaced pitch pine groves on many of our serpentine barrens are a perfect breeding ground for southern pine beetle infestation. Without fire management to maintain open savanna-like conditions, the tightly-packed pitch pines tend to be stressed, and vulnerable to beetles. Last year, at Nottingham County Park, an infestation took off and has now killed almost all of the mature pitch pine in the park. While saplings and seedlings will survive the infestation, huge numbers of dead snags have been left behind, and are now being logged off. Chester County is retaining Roger Latham, a mid-Atlantic grasslands expert, to manage the post-logging restoration, and we hope that the end result will be large gains in healthy serpentine grassland and savanna. However, the loss of so much pitch pine in a short time will put great pressure on pine-dwelling and -feeding birds and insects.
The pine beetle has also been trapped at Goat Hill, and has caused tree mortality places there, including damage observed by an FSLSB work crew last winter. The Pennsylvania Bureau of Forestry is working on a management plan for the area to reduce stand density and prevent another outbreak. That said, pine beetle infestations could appear in any pine stand, on or off the serpentine barrens, during the summer. Adults have been trapped last year, in Chester County, as far north as French Creek State Park. Be on the lookout when hiking in the barrens, and inform neighbors and landowners in the vicinity. Examine any pine trees showing yellowing in the crown. Popcornlike resin tubes, as shown in this observation, can be seen on the bark of attacked trees. See DCNR's fact sheet for other signs of pine beetle attack. If you find a pine beetle infestation in the area, please contact the PA Bureau of Forestry's Division of Forest Health; if it's in or near the serpentine barrens, please consider leaving a comment here as well.
On a brighter note, a warm welcome to @bobobaby who has recently joined the project and has been sharing a wealth of observations from many years at Nottingham County Park, particularly birds and insects. Marian is responsible for many new Chester County insect records at BugGuide and has a great eye for moths and many neglected insects. You can see her observations in the project listing (and our vastly expanded species list!) but I thought I'd share a few favorites:
- An armored-looking grasshopper
- A glorious silkmoth
- A pileated woodpecker (these at least have been having a field day with the pine beetle infestation)
Many thanks from the Friends, and don't forget to spare a little time from your rich, mesic woodlands during spring ephemeral season for the serpentine barrens, to look for arrowleaf violets and Michaux's stitchwort blooming and mourning cloaks coming out.
