Shhh…don’t tell the kids, but there’s a group of tiny beetles working tirelessly to make sure live Christmas trees arrive healthy. Lady beetles have become biological blessings for tree growers struggling with pine needle scale.
Those who don’t know better might think infested trees have been frosted like those often seen in fancy department store windows. Infested needles become covered with oystershell shaped scales which serve as armor for a creepy insect that sucks the life from the plant and can cause branch death.
One of the biological insect elves is the twice stabbed lady beetle, a jet black beetle with two red spots that is native to Illinois. A more aggressive scale predator is the solid black lady beetle named Lindorus lopanthae.
Ron Evans, a Christmas tree grower and Lindorus dealer, says a Lindorus beetle will scuttle across the needles like mini vacuum gobbling up the scales as it goes. He first noticed the scale on his 100,000 tree farm called Four E’s Trees in the mid-1990’s.
The scales overwinter as eggs, so dormant oil has little effect. Pesticides work, but require multiple and precisely timed sprays. Over time, Evans found more and more pesticide sprays were required with less and less effectiveness.
Scotch pine, red pine and Austrian pine are especially susceptible to the pine needle scale, but the pest can infest spruces and firs too. Evans says he was burning 1500 to 3000 trees ruined by scale before beetles battled back.
"Our first Lindorus beetle introduction was like a miracle," he says. Releasing several thousand Lindorus beetles in the late spring to early summer keeps Evans’ trees scale free and salable. The beetle must be released annually because it doesn’t survive the winter—which also means it doesn’t go home with tree customers as an uninvited house guest.
Evans says the beetles are elusive and tend to hide from observation. It is seeing the results of their work that results in true believers.