Ips Engraver Beetles
Georgia Forestry Commission Forest Health Monitoring Factsheets
Written by Terry Price, Georgia Forestry Commission
Adapted for the web by the Bugwood Network
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(Ips avulses, Ips pini, Ips grandicollis, Ips calligraphus,)
Ips engraver beetles are members of the bark beetle family and like the southern pine beetle, can do considerable damage under the right set of circumstances. There are four species found in Georgia (Figures 1-4). They bore under the bark of pines and construct galleries very typical of each species (Figures 5-8). Generally, they infest pines that have been struck by lightning, damaged by logging activities, storms or drought and root diseases. Unlike the southern pine beetle that is capable of killing several hundred acres of trees, Ips infestations are usually small (involving < 25 trees). However, during droughts, Ips outbreaks have been recorded killing thousands of trees statewide.
Figure 1
photo by Gerald J. Lenhard |
Figure 2
photo by Ron Long |
Figure 3
photo by Gerald J. Lenhard |
Figure 4
photo by David T. Almquist |
Figure 5
photo by Ronald F. Billings |
Figure 6
photo by Kenneth E. Gibson |
Figure 7
photo by Gerald J. Lenhard |
Figure 8
photo by Ronald F. Billings |
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The small southern pine engraver, Ips avulsus, attacks logging slash, young crowded stands or the tops of larger trees, particularly those infested with other species of bark beetles. Small trees are killed but larger trees often survive with just the upper third of the crown killed (Figure 9). Trees along power lines are often attacked following pruning. This species of Ips is found throughout Georgia.
The pine engraver, Ips pini, occurs in northern Georgia and attacks all species of pine growing there. Outbreaks can occur following drought or storm damage.
The southern pine engraver, Ips grandicollis, is found throughout Georgia and likes to breed in logging slash and other damaged trees.
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Figure 9
photo by Ronald F. Billings |
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The six-spined engraver, Ips calligraphus, is probably the most aggressive of the Ips beetles and is the largest. It is often the first species to attack drought stressed trees. During an outbreak in Georgia in the early 1980's, this beetle was recorded killing trees in spots up to 5 acres in size. It (along with Ips avulsus) is the species most often associated with Heterobasidion annosum (formerly annosum root rot) in thinned pine stands. Trees infected with root rot can be identified by thinning crowns (Figure 10).
Since most Ips infestations are small and scattered, control is often not economical in forest stands. The majority of Ips infestations, unless associated with annosum root rot, subside on their own after a few weeks. If they continue for several months to a year or longer, then root rot is probably present in the stand.
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Figure 10
photo by Edward L. Barnard |
Damage from Ips beetles can be minimized or avoided by preventing pine stands from becoming overcrowded and stagnated. Keep in mind though, that thinnings are stand disturbances and can attract Ips during the summer months. Also, if the site is high hazard for annosum root disease, stumps should be treated with Sporax at the time of thinning or the thinning should be done during the summer to minimize the risk of getting root rot. If root rot develops in the stand then Ips are most likely to become an ongoing problem and in many cases a clearcut is warranted.
Yard trees infested with Ips should be removed as soon as possible. Since Ips beetles are capable of attacking trees from top to bottom, insecticides are ineffective unless the entire length of the tree is sprayed. This is not recommended in urban settings due to the possibility of pesticide contamination to birdbaths, feeders, swimming pools and people.
Onyx insecticide (bifenthrin), is registered for use against Ips beetles and other pine bark beetles in yard or ornamental pines.
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