No. 2/May 5, 2021

Modified Growing Degree Days (Base 50⁰ F, March 1 through May 2)
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.

Phenology and Insect Management
Have you ever heard sayings such as "plant corn when oak leaves are the size of squirrels ear" or "apply crabgrass preventer when forsythia are blooming"? Sounds like old folk-lore but actually there is a science behind these statements. Phenology is the study of periodic plant and animal life cycle events and how they relate to seasonal/environmental changes. Rather than planning annual gardening tasks solely by the calendar, scientists have found correlations between temperatures and certain events by observing such things as bird migration, plant budding, flowering and fruiting and insect activities. American Indians observed nature and determined that soil was warm enough to prevent corn seeds from rotting at the same time oak leaves were emerging in the spring. Unknowingly they were using a phenological indicator. Oak leaves were a visual cue that told them it's time to plant corn.

Boxwood Leafminer
Boxwood leafminer (Monarthropalpus flavus) is a tiny midge that can harm boxwoods in its larval stage. The adults emerge in the spring around the time weigela is in bloom. Females lay eggs under the surface of a leaf and larvae feed on the tissue within the leaf. Larval feeding causes a raised green blister that can be seen on the leaf’s surface. The blister may become discolored or flake off later in the season. The leafminers overwinter within the leaves as larvae. They have one generation per year in Illinois.

Getting to Know Common Wasps
Throughout the summer you may encounter many different types of wasps. These wasps can look similar at first glance, but they often have very different natural histories and behaviors. While one wasp species might be aggressive and sting, another may be more interested in the food you’re serving at your family picnic or the juicy spiders in your garden. The following descriptions are intended to help landscape professionals and gardeners identify a few common wasps and determine whether they are problematic, neutral or beneficial in your shared space.

Purple Weed Blooms Abound
It’s been a great spring for the color purple. The redbud trees are in full bloom and looking glorious in the central part of the state now. But for several weeks, the ground has been purple as well due to a few cool-season weeds that seem to be enjoying the mostly moderate temperatures we’ve been having. The landscape colors have been striking. Of course, pollinators appreciate these early season blooms too! I’ve recently witnessed some confusion surrounding the identification of the following weeds, so a little review could be useful.

Mayapple Rust
You probably won't find mayapple (Podophyllum peltatum) in a typical landscape. However, this herbaceous perennial is common in many woodland areas. The plant emerges in early spring to capture sunlight before trees canopies above produce leaves and shade. Mayapple then senesces and goes dormant by mid-summer. I recently encountered numerous mayapple colonies, with their unmistakable umbrella-like leaves, while walking through my neighbor's wooded lot.

Jumping Worm Update
Jumping worms were first identified in Illinois in 2015. These invasive earthworms have been confirmed in several counties across the state, and observations suggest eggs can overwinter in warmer parts of the state. Jumping worms are native to East Asia. They have been sold in the United States as bait under the names crazy worm, Alabama jumper, and snake worm. The worm has characteristic coloration and behavior. Adult worms are approximately the same size as other naturalized earthworms, but are much darker. Most of the body is dark gray or brown, with a milky white or light gray band of tissue (the clitellum) circling the body. The clitellum is smooth, compared to other species where the clitellum is raised compared to the body. When disturbed, jumping worms become very active, wriggling and thrashing vigorously.

Easter Lily Care
If you were gifted an Easter lily (Lilium longiflorum) in April, you might be wondering what you do with it after it blooms. Often, they are tossed into the trash as a one-hit-wonder, but these lilies have the potential to bloom again in the summer or the late fall, providing the plant and weather cooperates.