The Southern Pine Beetle Reaches Cape Cod: How to Spot It and Stop It

The southern pine beetle (Dendroctonus frontalis) is smaller than a grain of rice, yet it can do massive damage to forests. It has been a well-known foe in the southern United States for centuries, but it is a new enemy in the Northeast.

Moving north

The beetle was first recorded in the southeastern United States in the late 1700s. Native to the Southeast, it has spread up the East Coast in recent decades as winters have grown warmer.

History helped set the stage. European settlers cut down many of the original forests, which were mostly trees such as oak and hickory that naturally resist the beetle. Farming changed the soil, and pines that the beetle can attack grew back in their place. Infestations began in New Jersey and New York about a decade before this article was written; in 2023 there were outbreaks on Martha's Vineyard and Nantucket; and early in the year of writing an infested tree was found at Pilgrim Heights, in Truro, inside Cape Cod National Seashore.

Where the southern pine beetle has damaged forests in the United States. U.S. Department of Agriculture Forest Service.

What to look for

The beetle itself is hard to spot — an adult is less than half the size of a grain of rice — and it looks different at each stage of life:

• egg: white;
• larva: crescent-shaped, with a dark red-brown head;
• pupa: white;
• adult: light brown to black.

The damage is easier to see. The first sign is usually pitch tubes — resin that oozes from the bark like popcorn, the tree's natural defence against attack. Peel back the bark of an infested tree and you may find S-shaped tunnels called galleries, which look like intricate mazes. Females bore them to lay their eggs, and give off pheromones that draw males to the tree. An infested tree can die quickly. The beetles often pick weakened trees, but not always, and they like to attack many trees in one area; they have killed acres of trees in very short periods. For Cape Cod an outbreak is especially dangerous, because many species depend on its pitch pine barrens.

A look-alike

The southern pine beetle is often mistaken for the black turpentine beetle, familiar in the Northeast. The differences:

Finding it early

There is no need to wait for an outbreak to confirm the beetle is present. Lindgren funnel traps, a series of funnels hung between two trees with a preservative such as ethanol at the bottom, attract beetles that take the trap for a tree; they must be checked regularly. Aerial and ground surveys can find beetles at early and later stages — but too often infestations of single trees or small groups are caught too late and grow into outbreaks that affect large areas of forest.

Treating an outbreak

• Prescribed burns — planned, carefully managed fires — can combat an outbreak and strengthen pitch pine forest.
• Felling: "cut and remove" takes infested trees off the site to be processed; "cut and leave" fells them where they stand when they cannot be moved.
• Thinning pine stands spaces the trees out, making it harder for beetles to signal each other with pheromones, find each other and attack in large numbers. Thinning is used against the beetle across the country.

What you can do

With average temperatures rising, the beetle will remain a threat to New England. Early detection is the best way to keep it contained while a response is worked out.

• Watch for signs. If you see a tree with pitch tubes or other symptoms, report it to the Massachusetts Department of Conservation's Forest Health program.
• Don't move firewood. Use local firewood at campsites and bonfires rather than bringing it from elsewhere.

Corrected: the article spells the trap "Lindegren"; it is the Lindgren funnel trap.

Words on this page from people and organisations outside the federal government are paraphrased; rewritten in hubnx's own words.

Sources

• Charlotte Hohman (NPS) and Sara Abbitt (AmeriCorps Cape Cod), "The Southern Pine Beetle: The Tree Killer," National Park Service, Cape Cod National Seashore. https://www.nps.gov/articles/000/the-southern-pine-beetle-the-tree-killer.htm
• The article's photographs, from state agencies, universities and other organisations, are not reproduced here.