Pine Cone Beetles (Conophthorus spp.)

Members of this genus are the only beetles that attack healthy living cones in the South. Two other beetle genera, Ernobius and Pityophthorus, often implicated in causing pine conelet and cone losses, are secondary invaders of dead and dying conelets and cones.

White pine cone beetle, Conophthorus coniperda (Schwarz)(1, 32)

BIOLOGY. - Adults emerge in the early spring. Over a period of about 30 days, each female attacks several cones, laying eggs in some or all of them. The female beetle constructs a gallery down the cone axis, laying her eggs in from 1 to 24 niches cut into the gallery walls. The larvae feed on both seed and cone tissues. When cones are scarce, conelets are attacked but no eggs are laid in them. There is one generation per year, and the new adults overwinter in the infested cones.

INSECT IDENTIFICATION. - Adult beetles are about 3 to 4 mm long, shiny black, and covered with moderately long erect hairs. The head is directed downward and may not be visible from above. Larvae are creamy-white, legless, and somewhat C-shaped.

DAMAGE IDENTIFICATION. - The beetles always attack the base of the cone where it joins the stalk, usually on the underside. The entrance hole is surrounded by a characteristic doughnut-shaped mass of resin-soaked light-brown frass. Attacked cones soon wither and die. Infested cones feel spongy, and the interior tissues are completely destroyed as larvae near the completion of their development.

IMPORTANCE. - In the South, the white pine cone beetle is a serious problem in eastern white pine seed production areas, and its occurrence is increasing in seed orchards. Damage to eastern white pine cone crops in the New England States has been particularly devastating.

Attack of eastern white pine cone. (5X)