A tree-killing invasive insect, the hemlock woolly adelgid (HWA), was found for the first time in Indiana on a landscape tree in LaPorte County in mid-April.
Since its introduction to the Eastern United States in the mid-1920s, the HWA has infested about half the native range of Eastern hemlock. In Indiana, forests containing hemlocks are scattered throughout the southern half of the state.
The finding of the tiny aphid-like insect, which destroys native hemlocks by feeding on the tree sap at the base of the needles, was confirmed by the USDA Animal Plant Health Inspection Service (APHIS).
The insect was identified on a single hemlock as a result of a homeowner's report. The infested tree may have originated from a landscape planting in Michigan and been brought into Indiana about five years ago. Preliminary searches have revealed no other infested trees in the area, but an extensive survey is underway.
"Fortunately, this find occurred outside of the native range of hemlock trees in Indiana, which greatly increases our chances of preventing spread to them," said Phil Marshall, state entomologist for the DNR.
HWA is easily spread by wind, movement on birds and mammals such as deer, and especially by human activities. Marshall emphasized the importance of limiting human movement of infested plants in spreading all invasive forest pests.
"HWA will be very destructive if it reaches our native hemlocks, but the more people who become aware of the dangers of moving plant material and firewood over long distances, the better chance we have at protecting our forests," Marshall said.
Named for the cottony covering over its body, HWA somewhat resembles a cotton swab attached to the underside of young hemlock twigs. Within two years, its feeding causes graying and thinning of needles. Highly infested trees will stop putting on new growth, and major branches die, beginning in the lower part of the tree. Eventually the whole tree is killed.
If you suspect an HWA infestation, call the Indiana DNR Invasive Species Hotline at 1-866-NO-EXOTIC.
For more information, see Michigan DNR's HWA Page (www.michigan.gov/dnr/0,4570,7-153-10370_12145_25065-33881--,00.html
), HWA in Hoosier National Forest (www.fs.usda.gov/Internet/FSE_DOCUMENTS/stelprdb5339105.pdf
Indiana's DNR website is being updated with HWA information.