Phenotype ratio for elytral coloration among reared offspring of Phymatodes testaceus suggests that this trait is controlled by a single gene with a dominant allele producing brown elytra and a reeessive allele for blue elytra. The brown-elytra phenotype previously has been reported as recessive in this species.
Gosling, D. C. L.
"Notes on the Genetics of Phymatodes Testaceus (Coleoptera: Cerambycidae),"
The Great Lakes Entomologist: Vol. 19
, Article 5.
Available at: http://scholar.valpo.edu/tgle/vol19/iss1/5