There is a size correlation which determines whether males become patrollers or hoverers. Patrollers tend to be larger so that they can better protect and copulate with emerging females. Smaller males are usually unable to compete as well, and so have to make the best out of a bad situation; thus, they become hoverers. Each group has a different set of behaviors. The patrollers move over a large space containing many other patrollers. Usually, patrollers will frequent the same spots over the course of their lives. Since the area is so large, the cost to defend it against other patrollers would be much greater than the potential mating benefits, so the patrollers show very little territoriality. Patroller males will usually only fight when a breeding female is near. In contrast, each hoverer stakes out an area of about one meter in diameter. These areas don’t overlap with other hoverers. Any fast moving object (i.e. bee, dragonfly, leaf, etc.) that enters a territory will be quickly chased. The chase allows the male bee to determine if a female is unmated, or if an enemy male is in his territory. If it is a male bee, the territory owner will chase it out, but not beyond the boundary of the territory. What is interesting is that every day (or even every several hours) the territory holder will abandon the area to establish a new zone. Often the male will never return to the vacated area, and it will be taken over by another male. This shows that hoverers show a low site tendency but strong territoriality. A balanced ratio of patrollers to hoverers is maintained, and thus, this ratio is an evolutionary stable strategy. If more males become patrollers, then the hoverers will benefit from the reduced competition, and the hoverers' genes will spread until the stable ratio is returned to. The same thing will happen if more males become hoverers.
They are large (up to 3 cm), fast-flying bees, distinguished from the closely related genus Epicharis by the absence of long, whip-like setae that project backwards from just behind the eyes. They are commonly encountered bees in American deserts, and are active at very high ambient temperatures when many other species are in hiding. They can often be seen in large numbers on desert-willow (Chilopsis) and palo verde (Parkinsonia) blossoms. Bees of this genus are of some economical significance in pollinating crops such as Brazil Nut (Bertholletia excelsa) and Cashew (Anacardium occidentale, pollinated by C. tarsata among others).
The two categories of behavior for C. pallida males are patrolling and hovering. These strategies are also used to find mates. In one category (the patrollers), male bees will patrol 3–6 centimeters above the ground in search of sites where buried virgin females will emerge. When a male bee finds such a site, he will dig 1–2 centimeters through the soil by gnawing at the surface with his jaws and using his forelegs to remove dirt from the excavation. If a female is found, he will attempt to mate with her either on the surface or at a nearby flower or tree. Other patrollers will sometimes attempt to steal a digging spot that another bee has found. If a bee has already found a female, another patroller bee may separate the male from the female so that it can copulate with the virgin. More often than not, the female (once found) will mate with either the male that found her or with an intruder.