This uncommonly encountered milkweed beetle is found in western Oklahoma and the panhandle region of Texas.
Forty-nine individuals were found in association with T. femoratus
LeConte on Asclepias latifolia
: Dickens Co., Double Rafter Ranch, 30-VII/29-VIII-79, 2/8-VII-80, [Marlin E. Rice]. Chemsak (1963) indicated that when a single host is utilized among two sympatric milkweed beetle species, one species is usually much less numerous than the other, and during a two year period, ca. 200 A. latifolia
growing in a fallow field, yielded fewer T. mandibularis
than T. femoratus
, with the ratio being 1:3.2. (1)