By Wendy Langhans
The other day, my Dad and I were exploring Frog Alley, part of the Vernon Wildlife Area in southeastern Wisconsin. We spotted some Canada Goldenrod (Solidago canadensis), one of the most common of the 24 different species of Goldenrod in Wisconsin.
And true to their name, these flowers brightened the lush green meadow with deep golden swatches.
When you look closely at the goldenrod stems, sometimes you see a tumorous swelling, an round, apple-shaped gall, that houses the larva of Goldenrod gall fly . The gall story begins earlier in the spring, when the female Goldenrod gall fly (Eurostra solidaginis) lays her egg in the tender terminal bud of the young Goldenrod plant. From there, the egg hatches and the larva chews down through the bud into the stem. The gall forms in response to the larva’s saliva. Sometimes, these galls “can reduce or even completely prevent goldenrod from flowering and producing seeds.”
But why do some Goldenrod have galls while others do not? Earlier in the Spring, when the gall flies are laying their eggs, some goldenrod “duck” and hide by bending their terminal buds downwards, forming a green candy-cane shape. Later in the summer, the stems straighten up in time for flowering. Scientists have “shown that candy-cane stems are roughly twice as resistant to three common species of gall flies as are the more common non-ducking, or ‘erect,’ stems.”
I enjoyed explaining all this to my Dad. (To be honest – perhaps I was showing off just a little bit). But, as usual, he had the last word: “You know, Wendy, ice fishermen used to harvest the goldenrod stems in the fall and store them in their equipment sheds. Later in the winter, they opened the galls and used the grubs as live bait. They were very good for catching pan fish.” I checked around and, as usual, he was correct; the gall fly larva overwinter inside the gall and emerge the following spring. Those fat grubs would make an attractive bait, especially when the ground was too frozen to dig for earthworms. I hate to admit it, Dad, but you were right again.
Upcoming Outdoor Events:
Saturday, August 7, 6:30-8:30 AM. Morning stroll. Pico Canyon. Get out in the park before the heat of the day. Beginners are welcome. Bring water and wear closed-toed shoes. Meet in the parking lot at Mentryville. 2 hrs. For map, click here.
Trail Maintenance Schedule. Come join our volunteers as they help maintain our trails. Contact Steve at firstname.lastname@example.org for time and place.
Wednesday mornings, August 4, 11, 18 & 25.
Saturday mornings, August 14 & 28.
You can listen to stories like this every Friday morning at 7:10 a.m. on “The Hike Report”, brought to you by your hometown radio station KHTS (AM1220) and by the Mountains Recreation and Conservation Authority.