I'm sure everyone has noticed that Chicago has survived the deep freeze of the Polar Vortex and now is a festival of slush and ice as we get a little thaw. This is the snow in action:
I admit it. I LOVE winter! I love warm socks, bundling up, frozen eyebrows - all of it. I've shoveled 18 inches of snow so far, my favorite aerobic activity. All my new perennials in the rain garden are tucked under a nice insulating blanket. The bunnies are eating the roses as usual.
What gets my horticulture heart stirring is the string of negative temperatures. I've been talking with folks at The Morton Arboretum and elsewhere about what the chances of this cold snap to kill off the big bad insects. So far, the news is cautiously positive. Bagworm and gypsy moth populations will definitely be knocked back as they overwinter on exposed trunks and branches. Japanese beetles, however, are tucked under a nice blanket of snow and soil, so they'll unfortunately, be just fine.
The burning question is will this cold kill emerald ash borer. Well, maybe. Some. We shall see. Here's information from a study from the U.S. Forest Service and an independent paper discussing their cold tolerances. Pretty much we had to get down to around -20 to see a significant impact. We got close at around -16, so maybe some of the evil little critters got zapped. If you're treating your ash trees, I wouldn't count on this winter saving your tree. Sorry. At least the oaks will have less gypsy moth to deal with!