|Ips Bark Beetle
IMPORTANCE: Pines of all
ages and sizes are attacked by Ips
bark beetles (Ips grandicollis,
calligraphus and avulsus). They
usually attack injured, dying or
recently felled trees, and logging
debris. They often kill only a few
trees in a given spot, but under
certain conditions become epidemic
and destroy hundreds of trees.
Damage is very high and compounded
by the blue-stain fungus they carry
that degrades lumber from infested
beetles are easily recognized by a
scooped out rear end surrounded by
spines. Black to reddish brown
adults vary in size from 3/32 to 1/4
inch in length. Adults not fully
mature, found under the bark, are
usually yellowish to light brown.
Fully-grown larvae and pupae are
yellowish white and vary from 3/32
to 3/16 of an inch in length. Eggs
are very small and white.
SIGNS OF ATTACK: Infested trees
usually have numerous white to
reddish brown pitch tubes, about the
size of a wad of gum, on the bark.
In trees of low vigor, pitch tubes
may be lacking and the earliest
signs will be reddish bark crevices
at the tree’s base.
beetles are attracted to weakened
trees and chew round holes through
the outer bark into the cambium
layer. “Y” or “H” shaped egg tunnels
are in the soft inner bark parallel
with the grain of the wood, and
generally free of boring dust. The
distinct gallery pattern is used for
identification purposes even when
larvae and adults are absent. Eggs
are laid singularly in small egg
niches cut along the main tunnel.
Larvae hatch and feed in generally
distinct lines. Larvae feeding
tunnels are usually filled with
boring dust. Larvae mature, pupate
and transform to adults in 25 to 40
days, depending on the temperature.
Emerging adults may or may not
attack nearby trees.
parasites, diseases and starvation
take a toll on Ips beetles, but
usually not until the tree is beyond
saving. These factors, changes in
weather conditions and proper
harvesting practices can reduce Ips
attacks and timber losses. Salvage
cutting and good forest management
are the most practical control
Photo Credits: David T. Almquist,
University of Florida; Tim Tigner,
Virginia Department of Forestry; G.
Keith Douce, The University of
Eastern Forest Environmental Threat
Forest Encyclopedia, USDA Forest Service
Forest Health Protection-USDA