Southern pine beetle

What is southern pine beetle?

Southern pine beetle is a tiny native bark beetle, about 1/8 inch long. CT DEEP calls it the most economically destructive insect in the Southeast, and in recent years it has spread north into the Pine Barrens of New Jersey, Long Island and Connecticut. PA DCNR calls it an important native bark beetle that prefers southern yellow pines but can attack any pine.

One female starts an attack and gives off a scent that draws in many more beetles. Healthy trees often push them out with resin, but stressed trees, or very large numbers of beetles, can overwhelm a pine. The beetles carve S-shaped tunnels under the bark and carry a blue-stain fungus. Trees that are successfully attacked can't be saved.

In the South it can have six or more generations a year (CT DEEP); NC State reports three to five in North Carolina, starting in spring about when redbuds and dogwoods bloom. NC State says attacks usually target trees at least 15 years old, especially stressed trees. How many generations it has this far north is still unknown.

Signs and damage

• Popcorn-sized lumps of white resin (pitch tubes) on the bark
• Fine reddish-brown boring dust in bark cracks and at the base of the tree
• S-shaped tunnels under the bark
• Needles that yellow, then turn orange-brown to reddish-brown, often on groups of trees
• Blue-gray stain in the sapwood from a fungus the beetle carries

Southern pine beetle identification: what to look for

• Adult: Stout, short-legged bark beetle about 1/8 inch long, dark reddish-brown, with a notched front of the head and a rounded rear end. Hard to see on the tree.
• Larva: Legless, wrinkled, curved grub about 1/8 inch long with a glossy reddish-brown head, under the bark.
• Signs: White pitch tubes, reddish-brown boring dust, S-shaped galleries, many small emergence holes, blue-stained wood.
• Damage: Needle fading and drop; attacked trees die.

Life cycle

Complete life cycle of egg, larva, pupa and adult. A pioneer female bores in and releases a pheromone that draws a mass attack. Females lay eggs along S-shaped galleries; larvae feed under the bark, then adults leave to attack new trees. In warm parts of the US there can be six or more generations a year. In Connecticut the number of generations and the stage that overwinters are not yet known.

When to look: Any time pines show fading needles, pitch tubes or boring dust, especially pitch, red and Scots pine.

Southern pine beetle look-alikes

A few things get mixed up with it:

• Other bark beetles: CT DEEP notes many bark beetles make similar galleries, so confirming SPB takes several signs together, ideally with an expert.

How to control southern pine beetle

Cultural control

• In woodlands, keep pine stands healthy; CT DEEP says managing stands to protect trees appears to be the best approach.
• For yard pines, NC State advises mulching and watering during very dry weather, not fertilizing, and avoiding bark injury, big grade changes and soil compaction around the roots.
• Cut infested trees as soon as beetles are found and debark or remove them right away (NC State), or chip them on site and remove the chips off-site (CT DEEP).
• Don't move infested wood. CT DEEP says wood from infested trees can be used as solid-sawn lumber once it is debarked.
• Avoid pruning pines during outbreaks; the University of Kentucky says the odors attract beetles.
• Clean tools such as hand saws used on infested trees (CT DEEP).

Biological control

• Healthy pines with strong resin flow can push out attacking beetles, but very large beetle numbers can overwhelm even resistant trees (University of Kentucky).

Chemical control

NC State says pyrethroid sprays on living trees are expensive but may be considered for valuable specimen pines, and that spraying after infestation has little practical effect. CT DEEP says arborists may recommend bark drench treatments before an attack succeeds, and trees already attacked can't be saved because there is no treatment for the fungus. Use only products labeled for this use; the label is the law. Treatment of trees is a job for an ISA Certified Arborist or licensed applicator. Muthler Landscaping does not treat trees or apply pesticides; see our pesticide applicator license guide.

Use only products labeled for this pest and this site; the label is the law. For trees, work with an ISA Certified Arborist. If you hire someone to apply pesticides, make sure they hold your state’s pesticide applicator license; the rules for each state are in our pesticide applicator license guide.

Prevention

• Don't move pine firewood or logs; see our firewood rules guide.
• Protect pine roots from compaction, grade changes and bark wounds during construction (NC State).
• Keep pine stands healthy; the University of Kentucky says practices that promote healthy trees reduce how often and how badly SPB hits.

When to call a pro

Call an ISA Certified Arborist for landscape pines, or a forester for woodlands, if pines show pitch tubes, boring dust and fading needles. Report suspected SPB in Pennsylvania.

Related guides: Tree database: mature size and planting distance · Pennsylvania tree identification · Firewood rules by state · All pests and diseases

Questions about southern pine beetle

Similar pests and diseases