Sphecius grandis, also called the western cicada killer, is a species of cicada killer wasp (Sphecius). The western species shares the same nesting biology as its fellow species, the eastern cicada killer (S. speciosus). S. grandis, like all other species of the genus Sphecius, mainly provides cicadas for its offspring. It forms nest aggregations and mates and broods once in a year, in July and early August. The wasp is on average to in length and is amber-yellow with yellow rings on its abdomen. Wasps in the genus Sphecius are not habitually aggressive and use their venom mainly to paralyse cicadas which they take back to their nests to feed their young. The females catch around four or more cicadas for provisioning, place them in brood cells and lay eggs in the cells. S. grandis is endemic to Central America, Mexico and the Western United States, and is found at a higher mean altitude than other species of Sphecius. The western cicada killer males emerge earlier than females, but generally die after only a couple of days. Sphecius grandis can be distinguished from S. convallis (the Pacific cicada killer wasp) by the coloration pattern of the gastral tergites. Formerly, the two species were distinguished on the basis of the number of tergites with yellow markings (five in S. grandis and three in S. convallis), but a more recent study showed that this character was insufficient to distinguish the two species. However, they can be distinguished by the density of the punctation on the first and second tergites. Taxonomy The western cicada killer was first described by American naturalist Thomas Say in 1824 in Madera Canyon, Arizona, as Stizus grandis. Its species name is the Latin adjective grandis meaning "large". It is one of five species of the genus Sphecius in North America. More recently, it has been suspected that the western cicada killer represents more than one species. It co-occurs with the eastern cicada killer (S. speciosus) and Pacific cicada killer (S. convallis) at Big Bend National Park in Texas. There the three wasps hunt and nest in the same locales, and the eastern and western cicada killers hunt the same cicada species. Analysis of mitochondrial DNA showed that the western cicada killer contains two divergent clades, which may represent distinct species. The two clades appeared to be split by the Rocky Mountains, with one occurring mainly to the south