Species Thyanta custator - Red-shouldered Stink Bug

Thyanta custator (Fabricius 1803)

10-11 mm(1)

highly variable

overwintering forms are often, but not always, brown, e.g.:

T. custator accerra is the wide-ranging subspecies, while T. custator custator is restricted to the Atlantic coastal plains and can easily be dinstinguised from T. custator accerra based on the presence of a black anterolateral pronotal margin, also present in T. calceata.

across NA (ME-BC to FL-CA to Guatemala) - Map (2)(3)(4)

polyphagous (recorded from dozens of spp. in 14 plant families)(5); minor pest of crops(6)

There are good biological reasons for keeping T. custator and T. pallidovirens as separate species although they are virtually indistinguishable morphologically. For the longest time, in the older literature, the common Thyanta species (coast-to-coast distribution) was called T. custator. Then Herb Ruckes revised the group and decided that the common species (coast-to-coast) was actually T. pallidovirens, with T. custator limited to Florida. He also divided T. pallidovirens into three sub-species which he called accera (with black spots on the abdomen, mainly midwestern and northern in range), spinosa (with spinose humeral angles, mainly southwestern), and pallidovirens, found on the west coast, which didn't have the ventral spots or the spiny angles. As with any subspecific characters, they tend to breakdown in the areas of transition. Dave Rider then reversed Ruckes and decided that the common coast-to-coast species was T. custator, and would have done away with T. pallidovirens as a synonym except for a study of the chromosomes by Ueshida at U. Berkeley. The California populations have 2n=16, whereas the midwestern population has 2n=14. So I basically follow Rider who kept the species names. If it's from California and doesn't have spines or spots on the abdomen I call it pallidovirens. Everything else is T. custator. (D.B. Thomas's comment)