Spruce bud worm moths collected as larvae from two species of host trees in four populations were mated in single pairs in two years. In 1980 but not 1981, more of the intra-population matings than the inter-population matings were fertile. Host tree origin was not a significant factor in the level of sterility.
Lorimer, Nancy and Bauer, Leah S.
"Reproductive Compatibility Within and Among Spruce Budworm (Lepidoptera: Tortricidae) Populations,"
The Great Lakes Entomologist, vol 16
Available at: https://scholar.valpo.edu/tgle/vol16/iss4/9