Identification
flightless (elytra without humeri), black, with lateral pronotal spines; associated with cacti
M. blapsides: mottled black and white elytra
M. semipunctatum: antennae with alternating black and white
M. appressum: elytra striated
in the remaining 3 spp., elytra not striated, antennae either entirely black or with white on antennomere 4 only
M. gigas: pronotal spines at least as long as antennomere 9
M. armatum: pronotal spines smaller than antennomere 9
M. annulatum: pronotal spines reduced to flat tubercles
"Another character that separates annulatum and appressum from the other species is the internally produced antennal scape (small inward-facing spur at the apex). Distribution can also be used in a few cases to narrow the choices - blapsides occurs only in southcentral TX (and south into Mexico), and armatum occurs in more easterly areas of the southwest while semipunctatum is in the more westerly areas of same (the two species are largely allopatric)." (Ted MacRae)
Range
Mexico (most spp.) to sw. US (east to TX & CO) to w. Canada (1 sp.,
M. annulatum)
(2)Food
cacti, esp. cholla, Opuntia
