No. 2/May 12, 2022

Modified Growing Degree Days
Insect development is temperature dependent. We can use degree days to help predict insect emergence and activity. Home, Yard, and Garden readers can use the links below with the degree day accumulations above to determine what insect pests could be active in their area.

Crane Fly Larvae in Turfgrass
Crane fly (Family Tipulidae) adults are a common sight during Illinois summers. They look like oversized mosquitoes with slender bodies and very long legs. While some people call them mosquito eaters, they actually do not feed as adults. The adults appear during the summer and spend their time mating and laying eggs. The eggs hatch in the fall and the crane flies overwinter as larvae.

Boxwood leafminer
Have browning boxwoods? Be sure to check for boxwood leafminer. I watched a row of boxwoods turn brown starting in late winter. I initially suspected winter injury, but when I looked closer, I found tiny, yellow/orange boxwood leafminer larvae in the leaves that I dissected.

Callery Pear Easily Noticeable in Bloom, and Threatening
You may have noticed white flowering trees nearly everywhere this spring. While they’re lovely, they can be too much of a good thing and possibly indicate an invasive problem. Callery Pear is in bloom now in Northern Illinois and was in full bloom very recently in Central Illinois. Blooms make these trees easily noticeable and bring awareness to the overabundant and worrisome population in many locations – typically where they don’t belong.

Hellebore Black Spot
You had me at Helleborus! Hellebores make wonderful additions to woodland gardens or landscapes with partial shade. I have had success growing them in a sloped flower bed mixed with hostas, coral bells, and hydrangeas. Their colorful blooms are one of my favorite signs that winter is giving way to spring.