are a common group of bark beetles that infest pine and spruce
rarely attacks healthy trees. Most problems with IPS occur to
newly transplanted pines or when trees are under stress, such
as from Dwarf Mistletoe.
generations of IPS can occur in a season.
general, preventive treatments for IPS are best applied by early
10 species of IPS occur in Colorado. Many are restricted to a
few tree species but others can be found in almost all species
of pine trees. They range from 1/8 to ¼ inch in length.
IPS winter as larvae. In mid-spring to early summer, adult beetles
emerge, fly about and begin to tunnel into logs, tree trunks and
branches. Male beetles move into the trees first and construct
a small (3-6 millimeter diameter) "nuptial chamber"
in the cambium of the wood. Female beetle then follow and construct
the radiating egg galleries, which often form a "Y"
or "H" - shaped pattern.
Egg and Larval Galleries Produced by IPS Beetle
eggs hatch, the small, white grub-like larvae begin to feed and
tunnel perpendicular to the egg galleries. The larvae and tunnels
increase in size as the insect grows and when full-grown, the
larvae pupate at the end of the tunnel. Adult beetles bore through
the bark and emerge to mate and infest other wood. As many as
three to four generations of IPS beetles may occur in a single
year. These generations overlap and all life stages may be found
in a single tree.
beetles are only able to successfully invade and breed in stressed
or dead and dying trees. Healthy trees are less attractive to
the beetles and are capable of "flushing out" the beetles.
Rarely, when high numbers of IPS beetles are present, mass beetle
attacks can kill apparently healthy trees.
begins to turn yellow or orange in late spring, or at other times
throughout the summer. (A seemingly healthy tree seems to turn
beneath bark is stained blue-gray.
galleries and insects may be found in attacked trees.
masses of sap on trunk mark beetle attack points.
may be found at the base of tree
prevent IPS beetle attacks, promote a healthy forest. This includes
thinning of trees and control of Dwarf Mistletoe. IPS beetle populations
can build up rapidly in felled timber and recently cut logs, such
as the diseased Dwarf Mistletoe tree that was just cut down.
best control of IPS beetle is prior to May 15th. The following
all felled timber and recently cut logs from your property prior
to May 15th. (ie: give to friend in town for firewood).
Burn wood in your fireplace or wood stove prior to May 15th.
all felled timber and recently cut logs with a mixture of Lindane
and Diesel (1 part to 14 parts). Spray on all bark surfaces. Temperatures
outside should be above 45 degrees F. Wood can then be burned
the next year. Wood does not need to be covered after spraying.
bark off of all logs and dispose of bark.