Southern pine beetle found west of Mississippi River

Significant numbers of southern pine beetles (SPB) in the Feliciana parishes captured in spring traps set by the Louisiana Department of Agriculture and Forestry were expected, but capturing the invasive insects in seven parishes west of the Mississippi River was a surprise. Although surprising, LDAF Forest Health Program Director Brent Cutrer said it isn’t time to sound an alarm. He said traps are set in pine dominant parishes for six weeks. This year a new pheromone was used, which might be the reason more SPB were captured. “It’s more potent of a chemical,” Cutrer said. Officials expected high SPB numbers in East and West Feliciana parishes because of the infestation the Homochitto National Forest in Mississippi. “Really all of the national forests in Mississippi have recorded SPB, but (Homochitto) that’s the hot spot,” he said. Except for an anomaly in Catahoula Parish, nothing has turned up over the past decade in parishes west of the Mississippi River. Being able to better attract the beetle is one of the factors Cutrer said he thinks why numbers increased in traps, but there’s also reason not to fret. Cutrer said clerid beetles are also captured in SPB traps. Clerids are predators to the southern pine beetle. “Of the seven parishes where SPB were caught (in state traps), only three of them had higher SPB counts than clerids,” Cutrer said.

Wood Johnson, U.S. Forest Service entomologist, said SPB attack the cambium layer of the tree and in great numbers can kill it. But healthy trees can successfully fight off SPB in small numbers. “They (SPB) may start in a stressed tree like a lightning strike, but with the right conditions, populations can rapidly grow and overwhelm the defenses of healthy trees,” Johnson said. The Forest Service sets traps on federal land, primarily in the Kisatchie National Forest, and complements LDAF SPB trapping on state and private lands in some areas. SPB counts in 2018 were very high in the Sicily Island Hills area of Catahoula Parish. A single trap caught 5,418 SPB in a six-week period, which is fewer than East Feliciana (5,919 SPB) but more than two traps captured in West Feliciana Parish (4,486 SPB). Both officials agree, however, that good management of forests is important to fight any pest. “Don’t manage your timber based on the market,” Cutrer said. “Manage it based on sound silviculture and optimal stand growth. Keep your stands vigorously growing.” Johnson said evidence suggests that SPB is west of the Mississippi River and “perhaps increasing in numbers.” Cutrer adds that more data is needed to determine risk, probably years more of monitoring. For now, forest landowners just need to keep watch. “Folks need to be vigilant, especially small private landowners with unthinned or overstocked loblolly stands,” Johnson said. “Those folks stand to lose the most, since every acre of timber counts and losses are costly. “When SPBs are a threat it’s best to follow the advice of your consulting forester and thin on recommended schedules rather than wait on optimal mill prices.” That vigilance is important for all landowners, Cutrer said. “When they don’t manage their stand optimally, they’re affecting their neighbors,” he said.