Pine Bark Beetles

Published: Friday, July 5, 2013 at 08:04 AM.

Florida is well known for its beautiful pine trees, many of which provide decorative shade for home grounds, not to mention significant revenue for timber and pulpwood growers.  We usually think of pines as being relatively trouble-free.  Unfortunately, several species of bark beetles are destroying pines throughout the south, including those in suburban landscapes.

Southern pine beetle is one of the most serious pests of pines in the United States, but normally is a scavenger of dying pines.  It becomes a pest when its populations increase. Dendroctonous beetles are distinguished by round posterious, in contrast to IPS beetles, the abdomens of which are concave posteriorly and have spines on the wing covers.  Adult beetles, active throughout the year whenever temperatures are above 58°F, disperse widely to in fest injured weakened of stressed trees.  When abundant, they can attack and overwhelm trees.  The presence of pitch masses on the tree trunk may indicate and attack.  Adults tunnel beneath the bark constructing frass-packed egg galleries in patterns resembling the letter S.  The tunneling quickly destroys the phloem and kills the tree.  My information on these destructive insects was provided by Extension Entomologist and Nematologist Dr. Eillen A. Buss with IFAS of the University of Florida.

Normally, these beetles inhabit forest areas.  But, they often migrate to home grounds.  If your landscape includes one or more pines, you need to learn how to recognize and cope with bark beetle infections.

Mature bark beetles are about the side of a grain of rice.  They range in color from reddish-brown to solid black.  Within the inner bark of most pines, the insect go through four life stages – egg, larva, pupa and adult.  The eggs are glistening white dots.  Larvae, or “grubs” as they’re commonly called are white and crescent shaped with glossy reddish-brown heads and no legs.

Pupae, which also are white, closely resemble the adult beetle shape.  Bark beetles mature in about month; and three to eight generations are born each year.  The adults have wings.  After they kill the tree in which they developed.  They fly off to other trees and start the life cycle again.

The first sign of bark beetle infestation are popcorn-sized lumps of pitch, called pitch tubes.  These occur at heights up to 16 feet.  Although pitch tubes do not appear during dry weather, a dust, which looks something like red sawdust collects in the bark crevices and at the base of trees that are suffering from beetle attack.

In the later stages of infestation, small feeding cuts, resembling tiny tunnels, appear on the inside of the bark.  The final sign, a sure mark of death for a tree, is change in the color of its needles, which turn from green, to yellow, to red and finally, to brown.



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