Since 2018, biologists from the Forest Health Program at the MA Department of Conservation and Recreation have been conducting surveillance trapping for southern pine beetles on Nantucket. You may have already noticed the traps this spring as they have just recently set lures and traps in three Pitch Pine forests across the island in an effort to detect these beetles if they have arrived here. We could use your help searching for potentially infested trees! The southern pine beetle (Dendroctonus frontalis) is a tiny, blackish-brown beetle, approximately 2-4 mm in size, that’s less than 1/8 of an inch and about half the length of a grain of rice.
As their name suggests, southern pine beetles are native to the southern US, with historic ranges extending as far west as New Mexico and Arizona, and as far north as Pennsylvania and southern New Jersey. Thanks to a warming climate, they are now beginning to march farther northward into New York and New England. Their populations can exist at low, endemic levels where they persist on weakened or dead trees. At low population levels, healthy trees that do become infested can usually ward off an attack by producing a resin that leaks out of the tree at the point where the beetle burrowed in through the bark. These sticky “pitch tubes” entrap and kill the beetles, and force them out of tree. However, a major outbreak at epidemic levels of southern pine beetles can very quickly overwhelm the defenses of a healthy tree, killing it in as little as two months. These outbreaks can move quickly through stands of trees, causing widespread damage to pine forests. To add insult to injury, the result of an unchecked infestation is a forest full of standing, dead and dry pine trees that then pose a major wildfire hazard.
The closest and most recent outbreak occurred in the Central Pine Barrens of Long Island, NY beginning in 2014 and has caused extensive damage to pitch pine forests throughout Suffolk County. Since that initial outbreak, regular monitoring has detected beetles as far north as the Albany Pine Bush area although an outbreak has yet to occur outside of Long Island. Massachusetts Department of Conservation and Recreation (MA DCR) has been conducting extensive monitoring for southern pine beetle presence throughout the state since 2015 in preparation for the inevitable arrival of this pest. Given the proximity of Long Island to coastal Massachusetts, it’s likely that Martha’s Vineyard or Nantucket could be the first to see southern pine beetles.
On your walks through conservation properties this spring and summer, you may notice some strange contraptions dangling from pitch pine trees. These black, plastic traps are called Lindgren funnel traps that use pheromone lures to entice any nearby specimens of these non-native, wee beasties to investigate the irresistible hormone scents. The beetles then enter the trap in search of the source of the scent, slip down through the funnels and drop in to a cup at the bottom filled with a preservative.
Photo: Danielle O’Dell
We check the traps on a biweekly basis and send off any potential specimens for expert identification by entomologists at MA DCR. As with all invasive species, our motto at NCF is early detection, rapid response. Controlling a pest after it has established is difficult and expensive, if not impossible. The sooner we can detect a species as it arrives, the better chance we have at getting ahead of it.
We have been monitoring for the beetles on Nantucket since 2018 and so far, only a single southern pine beetle was found in a trap in a pitch pine tree near the Water Tower between Milestone and Polpis Roads. The finding of a single beetle is not cause for alarm but certainly warrants continued surveillance. We can always use more eyes out looking for the signs of an infestation. Keep an eye out for pitch or white pine trees that have the following tell tale signs of infestation:
- sudden reddening or browning of all needles
- Pitch tubes or ‘popcorn-shaped’ resin masses on the bark all the way up the tree
- Scattered, tiny holes in the bark where beetles have entered the tree
- S-shaped trails or tunnels in the tissue of the tree underneath peeled away bark
Images courtesy of UMass Amherst website – https://ag.umass.edu/landscape/fact-sheets/southern-pine-beetle
The closely related but native Black Turpentine beetle (Dendroctonus terebrans) is present and very common on Nantucket and can also cause damage to pitch pine, as well as white pine and Japanese black pine, both of which are also present on Island. These beetles usually affect trees that have been weakened from stresses like constant salt spray and winter storms and the signs are fairly easily distinguished from that of southern pine beetles. For one, black turpentine beetles are a much larger beetle, nearly 3 times the size of a southern pine beetle. Damage is generally contained to the bottom 6 feet of the tree whereas the southern pine beetle damage will be found throughout the entire trunk. The exit holes scattered in the bark are much larger, as are the pitch tubes which are about an inch wide, white, and tend to ooze down the bark.
If (or when?) southern pine beetles arrive on Nantucket, measures to take in order to slow the progression of an outbreak are fairly extreme and will require a strong stomach as forests would likely look very different due to treatments and coordinated efforts between conservation organizations and private landowners alike. Recommendations from lessons learned on Long Island include:
- Winter felling of all infested trees, and cutting that tree in to sections on the ground to expose and kill the brood currently living in the tree
- Summer cutting of infested trees – not likely to kill the brood in the tree but disrupts pheromone production and the ability of beetles to communicate via pheromones
- Extensive thinning of pines and shrubs within an infested stand
The above graphic depicts two areas of southern pine beetle infestation on Long Island with different suppression efforts showing vastly different outcomes. The image on the left shows how quickly large areas can become damaged with no intervention. Whereas, more aggressive suppression efforts depicted in the image on the right shows far less spread of the infestation.
The pitch pine forests on Nantucket host unique communities of plants and animals. Over the last few years, our research as shown how valuable they are to endangered and rare species such as New England Cottontails and Northern long-eared bats. As you walk through these beautiful forests over the next few months, please help us by learning to recognize the signs of beetle infestations and if you see something, say something! Reach out to us at the Nantucket Conservation Foundation at (508) 228-2884 or email dodell@nantucketconservation.org.
The Nantucket Conservation Foundation is a private, non-profit land trust that depends on contributions from our members to support our science projects, conservation property acquisitions and land management efforts. If you are not already a member, please join us now! www.nantucketconservation.org