Ips pine bark beetle
Order Coleoptera: Family Scolytidae
Importance: Ips beetles are commonly found throughout the South. They usually attack injured or stressed trees, freshly felled trees or logging slash. Infestations are frequently initiated in trees stressed by lightning, logging injury or fire damage. Ips beetles usually attack and kill only one-to-a-few trees in a location. However, in areas in which trees have undergone severe drought stress, ice or wind/hail damage, they frequently buildup large populations and may kill large numbers of trees. Ips beetles are second only to the southern pine beetle in the number of trees killed by southern forest insects.
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Hosts: Ips beetles attack the major pine species grown in
the South. Evidence: Depending upon which of the four Ips species are involved, an infestation is initiated by adults attacking the tree trunk, the trunk and scaffold limbs or only scaffold limbs. Often, the first recognized sign of attack is yellowing or reddening of needles in tree crowns. Unfortunately, by this time most of the beetles have completed their life cycle (approx. 21 days to several months depending upon temperature) and emerged from the tree. Other signs of attack include the formation of amber, popcorn-shaped pitch tubes on the tree trunk, or if the tree is severely stressed, only the presence of small boring holes and brown boring dust found in bark crevices and on spider webs resulting from adults boring through the tree bark. Ips pitch tubes are ½ inch-or-less in diameter are formed as resin exuded as a defense against the beetles boring through the tree bark hardens. Identification: Ips beetles are one of three major groups of important pine bark beetles in the South. The rear end of adult Ips beetles are concave (scoopedout in appearance) with four-to-six pairs of spines on either side of the concaved areas. Adults are cylindrical in shape, usually dark browntoblack and range in length from 2 to 7 mm (0.10.3 inch). Other important pine bark beetles in the South are the southern pine beetle (SPB) Dendroctonusfrontalis Zimmermann and the black turpentine beetle (BTB) Dendroctonus terebrans (Olivier), which have rounded rear ends. Damage: Male Ips beetles initiate attack by boring through the bark and constructing mating chambers. From two to four females (depending on species) join each male. Egg galleries radiate out from the mating chamber with eggs being deposited at regular intervals along the sides of the galleries. The galleries usually groove the sapwood and are generally free of boring dust. Ips egg galleries are usually parallel to the grain of the sapwood and are roughly Y, H or I shaped (except for the small Ips avulsus). Ips beetles introduce blue stain fungus into egg galleries on which larvae feed and which will ultimately cause the death of the tree. Once Ips beetles successfully attack a tree and construct egg galleries the tree usually cannot be saved, even if treated with an insecticide to kill the larvae. |
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Contact your county extension office or your local state forestry commission/department for more information.
References
G. K. Douce. 1993. Pine Bark Beetles. Univ. GA, Coop. Ext. Serv., Col. Agr. and Envir. Sci., Bull. 1097, 8 pp.
Anonymous. 1989. Insects and Diseases of Trees in the South. USDA Forest Service Southern Region. Protection Report R9-PR 16. 98p.
Photo Credits
Image 1: Forest Insects and Their Damage Photo CD vol. 1 no. 88. Gerald Lenhard, Louisiana
State University.
Image 2: Forest Insects and Their Damage Photo CD vol. 2 no. 12. Ronald Billings, Texas
Forest Service.
Image 3: Forest Insects and Their Damage Photo CD vol. 2 no. 17. Ronald Billings, Texas
Forest Service.
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