Small Carpenter Bee

Ceratina dupla — the small carpenter bee — is one of about 350 species in genus Ceratina (the small carpenter bees — TINY relatives of the large 'true' carpenter bees in genus Xylocopa, see eastern carpenter bee and California carpenter bee in the Wild Files). The species is widespread across eastern North America from southern Canada south through the eastern US to northern Florida. Adults are 5-8 mm long (much smaller than the bumblebee-sized large carpenter bees), with the species' diagnostic features: SHINY DARK-BLUE OR DARK-GREEN METALLIC BODY (the body has a distinctive metallic 'jewel-like' appearance from structural coloration), small body size, and reduced hairiness compared to most other bees. The metallic coloration is one of the most-photographed features in NA solitary bee macro nature photography. The species is unlike its larger Xylocopa relatives in NESTING IN HOLLOW PLANT STEMS rather than in wood. Females excavate nesting tunnels in HOLLOW OR PITHY STEMS of various herbaceous and woody plants — especially elderberry stems, raspberry canes, sumac stems, dead goldenrod stalks, dead sunflower stalks, and other plants with naturally hollow or pithy stem cores. The species' small body size allows nesting in stems much smaller than the diameter of the large carpenter bee tunnels in wood. The species is one of the most-cited examples of MATERNAL CARE IN BEES. Unlike most solitary bees (which provide one-time provisions to developing offspring and then never return), Ceratina females provide EXTENDED CARE to developing offspring throughout the larval period. The maternal care behaviors include: PERIODIC INSPECTION OF DEVELOPING LARVAE (the female periodically visits the nest cells to check on larval development, similar to social bee behaviors), REMOVAL OF DEAD OR MOLDY PROVISIONS (the female cleans the nest of failed larvae or contaminated food provisions), and (in some Ceratina species) PROGRESSIVE PROVISIONING (the female continuously adds food to developing offspring throughout the larval period — a 'sub-social' behavior more typical of social bees like bumblebees and honey bees than solitary bees). The maternal care behavior is one of the most-cited examples of EVOLUTIONARY TRANSITIONS BETWEEN SOLITARY AND SOCIAL BEES — Ceratina represents an intermediate evolutionary state between fully-solitary bees (most NA solitary bees) and fully-social bees (bumblebees, honey bees), providing valuable insight into how social behavior evolved in Hymenoptera. The species is featured in essentially every modern textbook discussion of bee social evolution. Ceratina species are also major BENEFICIAL POLLINATORS — small body size and broad host plant range make them effective pollinators of many small wildflowers and small-flowered crops. The species is harmless to humans (very small, rarely sting, the sting is medically insignificant).