Window traps with ethanol were used to observe seasonal flight patterns of Corthylus punctatissimus in central Michigan. Flights peaked in early July with a second peak seven weeks later in late August. Similarly, wilting of attacked maple (Acer) saplings began to appear a week after initial Corthylus flights, and showed twopeaks, one in mid-July and again with another peak, seven weeks later, in early September. The second peak of activity is presumably from reemerged adults, and not a second generation.
Larsen, Stephen W.; Howell, Carol L.; Densmore, Kurt J.; and Roeper, Richard A.
"Seasonal Patterns of Flight and Attack of Maple Saplings by the Ambrosia Beetle Corthylus Punctatissimus (Coleoptera: Scolytidae) in Central Michigan,"
The Great Lakes Entomologist: Vol. 27
, Article 5.
Available at: https://scholar.valpo.edu/tgle/vol27/iss2/5