The pitted ambrosia beetle. Corthylus punctatissimus Zimmerman, infests woody saplings and shrubs 14 mm in diameter or less. The beetle bores an entrance hole into the main stem at soil level and constructs a main gallery tunnel which generally spirals downward in the stem. Egg-niche construction is followed by inoculation of symbiotic fungi and oviposition. The main stem of the host tree wilts as a result of the girdling activity of the beetle. Finnegan (1967) described the life history of C. punctatissimus infesting Acer saccharum Marshall in Ontario and Quebec.
Roeper, Richard A.; Zestos, Demetrios V.; Palik, Brian J.; and Kirkendall, Larry R.
"Distribution and Host Plants of Corthylus Punctatissimus (Coleoptera: Scolytidae) in the Lower Peninsula of Michigan,"
The Great Lakes Entomologist, vol 20
Available at: https://scholar.valpo.edu/tgle/vol20/iss2/3