Opuntia polyacantha for livestock when little other food is available. It will also grow in waste areas where good forage will not take hold. In fact, an abundance of the cactus indicates land that is poor in quality. Several insects attack the cactus, including the cactus moth "Melitara dentata", the blue cactus borer "Olycella subumbrella", and the cactus bug "Chelinidea vittiger". Opuntia polyacantha Opuntia polyacantha is a common species of cactus known by the common names plains pricklypear, hairspine cactus, panhandle pricklypear, and starvation pricklypear. It is native to North America, where it is widespread in Western Canada, the Great Plains, the
Opuntia engelmannii (state) to the Tamaulipan matorral in Chihuahua (state), in Mexico. In the Sonoran Desert, terminal pads face predominantly east-west, so as to maximize the absorption of solar radiation during summer rains. Although found occasionally in the Mojave Desert, it tends to be replaced by "Opuntia basilaris", which does not need the summer rain. The overall form of "Opuntia engelmannii" is generally shrubby, with dense clumps up to high, usually with no apparent trunk. The pads are green (rarely blue-green), obovate to round, about 15–30 cm long and 12–20 cm wide. The glochids are yellow initially, then brown with age. Spines