BLACK TURPENTINE BEETLE
BLACK TURPENTINE BEETLE, Dendroctonus terebrans (oliver), Scolytidae, COLEOPTERA
This beetle is robust, brownish to black with a barrel-shaped body, 5/16 to almost 3/8 inch long (the largest of the bark beetles attacking pine in North Carolina). There is no description of the egg. The larva is a legless, brown-headed grub. When full grown, the 1/2-inch long grub has brown bumps along each side of its body. The pupa is fragile, white and somewhat oval.
Turpentine beetles are capable of killing the best trees in a stand. However, attacks of this pest do not always prove fatal. Death of the tree usually occurs only when the infested tree has been weakened from other causes, or when so many beetles attack that the tunnels overlap and girdle the cambium layer under the bark. The needles of trees that are killed fade first to yellowish-green and finally to a reddish-brown. Fading usually begins 4 to 8 months after the initial attack, but sometimes it does not start until 12 months or more have passed.
Black turpentine beetles are attracted to the odor of resin at bruised bark or freshly cut stumps. They usually attack weakened or injured trees before spreading to nearby healthy ones. On occasion, they directly invade green, healthy trees. The beetles usually attack within 6 feet of the ground (though they can go as high as 20). They bore entrance holes into the soft inner bark and chew out tunnels between the outer bark and wood. Rows of eggs are laid in grooves on both sides of these tunnels over a period of several months. Grubs hatch in about 10 days. The young grubs feed together on the soft inner bark for 5 to 7 weeks, making broad, fan-shaped communal galleries. Pupation takes from 10 to 14 days, after which new adults emerge from holes chewed through the bark. The length of a life cycle is 3 to 4 months, depending upon the temperature (longer in cold weather). In North Carolina, there are 2 to 3 overlapping generations per year, and all stages of development can be found under the bark of infested trees throughout the year.
Often infested trees may be saved if control measures are applied in time. If only a small number of pitch tubes are present, the bark below the pitch tube can be shaved away until the tunnel or entrance is located, then chipping away the bark (with a wood chisel or similar device) will expose the gallery and the insects and they can be mechanically destroyed. Or the pitch tube can be struck soundly with a heavy rubber mallet or sledge. This crushes the pitch tube, closes the entrance tunnel, and squashes the beetles and grubs in the gallery beneath.
Since trees may be re-attacked, frequent inspection is necessary for at least 1 year. Wounds or breaks in the bark that may attract beetles can be painted with a standard tree paint. To protect trees from further infestation, the trunks can be sprayed with permethrin or bifenthrin. (Astro or TalstarOne). Dursban Pro may be available for non residential areas. Several home and garden products containing permethrin such as "Multipurpose Insect Killer" and "Eight" have pine or pine beetles listed on the label. It is probably a good idea to spray trunks of healthy pines nearby to prevent their infestation also. When using one of the following pesticides, follow label directions carefully. Do not apply to wet bark.
US Forest Service Leaflet #12
Florida Insect Note
© 2001 NC Cooperative Extension Service
July 1994; (Revised) 2001; August 2003
Web page last reviewed January, 2011 by the webperson.