Ceratina bees, commonly known as small carpenter bees, are a widespread group of insects. These diminutive bees often go unnoticed due to their modest size, typically only a few millimeters long. Despite their common presence, they are frequently overlooked. They are a distinct type of bee, separate from the larger, more commonly recognized carpenter bees.
Identifying Small Carpenter Bees
Small carpenter bees possess several distinguishing physical traits. Most Ceratina species range from 3 to 10 millimeters, making them significantly smaller than their large carpenter bee relatives (Xylocopa), which can exceed 20 millimeters. Their bodies are often sparsely haired, giving them a relatively smooth and shiny appearance compared to the dense, fuzzy coats of bumblebees or honey bees. The coloration of these bees typically includes metallic shades of blue, green, or black, sometimes with yellow markings on their faces or legs, which can vary by species.
Their abdomen is smooth and glossy, lacking extensive hair. When at rest, Ceratina bees often hold their wings flat over their backs, distinguishing them from other small bees that might fold their wings differently. Observing their flight pattern can also be helpful; they typically have a quick, darting flight. Differentiating them from other small, dark bees in a garden involves looking for these specific combinations of size, metallic sheen, sparse hair, and wing posture.
Nesting Habits and Social Life
Ceratina bees primarily utilizing the pithy stems of various plants for their homes. They prefer the soft, easily excavated centers of dead or dying plant stems, such as those from elderberry, sumac, bramble, or rose canes. A female bee will chew into the broken end of a stem, excavating a linear tunnel. She removes the pith material, creating a hollow chamber for her offspring.
Within this excavated tunnel, the female bee constructs a series of brood cells, separated by partitions made from chewed plant material and saliva. Each cell contains a provision mass of pollen and nectar, upon which a single egg is laid. Their subsocial behavior, where the mother bee remains with her developing offspring after laying eggs. She may guard the nest entrance, clean the tunnel, or even feed her larvae progressively, unlike solitary bees that seal the nest and leave. This extended maternal care can last through the larval and pupal stages, sometimes even into early adulthood, before the new generation disperses.
Ecological Importance and Human Interaction
Small carpenter bees contribute to ecosystem health as pollinators. They visit a wide array of flowering plants, collecting pollen and nectar, facilitating the reproduction of native wildflowers and cultivated garden crops. Their generalist foraging habits support biodiversity across various landscapes. Their presence ensures the successful setting of fruits and seeds for numerous plant species.
Unlike the larger carpenter bees, Ceratina bees are not considered pests. Their tunneling is confined to pithy plant stems, causing no harm to living plants or human structures. In fact, their excavation in dead stems can be seen as natural pruning or decomposition. These small bees are non-aggressive and rarely sting unless directly provoked, making them safe inhabitants of gardens and urban green spaces. Gardeners can support Ceratina populations by leaving cut or broken pithy stems in their landscapes, providing suitable nesting sites.