Deserts. Common. Diggers.
Name: ‘The Pallid Bee’ or ‘The Digger Bee’ (no official common name)
Family: Apidae (with: carpenter, honey, bumble bees)
States: Arizona, California, New Mexico, Nevada
Centris pallida are known for their vibrant, yellow-green eyes and pale fuzz as they buzz around desert palo verde – females are also known for the lovable ‘chaps’ on their rear legs which help them gather pollen.
C. pallida are some of the best bees at maintaining a stable body temperature; they are often found within 2 degrees Celsius of lethal overheating!
C. pallida females dig long tunnels to lay a single egg in a wax-lined cell, 8-10 cm under the dirt. These cells are provisioned with a soupy, orange-colored bread made of pollen and nectar. After sealing the cell, the mother fills in the whole tunnel with dirt and starts over for her next egg. Females often aggregate in the same area, collectively laying hundred of eggs in a relatively small area.
In early spring, the next generation of adults emerge and aggregate by the thousands to mate. Males emerge first, and begin searching the ground for females. Large males can smell females underground as they start to dig themselves out of their cells and will fight with one another to help dig her out and mate with her. Small males can’t afford to brawl so they employ a sneakier strategy! Hovering on the outside of the aggregation, they wait for escaped females to mate with instead.
Sources and Further Reading:
A friendly webpage written by C. pallida expert, John Alcock that summarizes his papers listed below.
Alcock J, Jones E, Buchmann S (1976). The Nesting Behavior of Three Species of Centris Bees (Hymenoptera: Anthrophoridae). Journal of the Kansas Entomological Society, 49: 469-474.
Alcock J, Jones E, Buchmann S (1976). Location before emergence of the female bee, Centris pallida, by its male (Hymenoptera: Anthrophoridae). Journal of Zoology, 179: 189-99.
Alcock J, Buchmann S (1985). The significance of post-insemination display by male Centris pallida (Hymenoptera: Anthophoridae). Z. Tierpsychol., 68: 231-43.
Alcock J (1976). The social organization of male populations of Centris pallida (Hymenoptera, Anthophoridae). Psyche, 83: 121-31.
Alcock J, Jones C, Buchmann S (1977). Male mating strategies in the bee Centris pallida Fox (Anthophoridae: Hymenoptera). The American Naturalist, 111: 145-55.
Chappell M (1984). Temperature regulation and energetics of the solitary bee Centris pallida during Foraging and intermale mate competition. Physiological Zoology, 57: 215-25.
Gilliam M, Buchmann S, Lorenz B (1984). Microbial flora of the larval provisions of the solitary bees, Centris pallida and Anthophora sp. Apidologie, 15: 1-10.
Roberts S, Harrison J, Hadley N (1998). Mechanisms of thermal balance in flying Centris pallida (Hymenoptera: Anthophoridae). Journal of Experimental Biology, 201: 2321-31.
Roberts S (2005). Effects of flight behavior on body temperature and kinematics during inter-mate male competition in the solitary desert bee Centris pallida. Physiological Entomology, 30: 151-7.