Hornet hornets may often be black and white. There is also a related genus of Asian nocturnal vespines, "Provespa", which are referred to as "night wasps" or "night hornets", though they are not true hornets. Some other large wasps are sometimes referred to as hornets, most notably the bald-faced hornet ("Dolichovespula maculata") found in North America. It is set apart by its black and ivory coloration. The name "hornet" is used for this and related species primarily because of their habit of making aerial nests (similar to the true hornets) rather than subterranean nests. Another example is the Australian hornet ("Abispa
Bald-faced hornet the queen's brood. In a sampling of seven "D. maculata nests", 20.9% of males were produced by workers. The percentage of males who were workers’ sons did not correlate with the time during which nests were collected or colony size. Because worker relatedness is so high in "D. maculata", workers are more related to other workers' sons than to the queen's own sons, and therefore worker policing of egg production does not occur. An explanation for the queen's near monopoly on male production is that worker production is costly and therefore reduces total colony reproduction. The cost toward worker production