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Small Carpenter Bees (Ceratina): Easy-to-Support Native Pollinators That Nest in Plant Stems

Unlike managed honey bees, most wild bees are solitary. The majority nest in ground; a minority are cavity nesters. Small carpenter bees (Ceratina) are among the easiest cavity nesters to support—they nest in plant stems.

Quick Facts

Genus: Ceratina
North American subgenera: Ceratinula, Zadontomerus, Calloceratina (22 species)
Upper Midwest/Northeast species: C. calcarata, C. dupla, C. strenua, C. mikmaqi, C. cockerelli (mainly Southeast)
Distribution: Worldwide except rare in Australia
Habitat: Near woodlands, gardens, meadows, prairies, old fields

When to Watch

Active early spring through fall. Visit first spring woodland wildflowers (hepatica, bloodroot).

How They Help

Despite tiny size (5–8 mm), they have relatively long tongues accessing both simple and complex flowers. Need continuous bloom succession and flower diversity. Females expend high energy nesting/provisioning—require ongoing pollen/nectar for themselves and offspring.

How to Spot Them

Adults: Shiny metallic blue/blue-green (except C. cockerelli black), relatively hairless, white/cream stripe between eyes. Females have fine pollen hairs on hind legs.

Larvae: Grub-like, pale yellow/cream, hidden in stems.

How to Attract Them

Provide nesting stems: When cutting back perennials in spring, leave 12–15 inches of stubble. Include variety of stem diameters—hollow for other cavity nesters, solid small stems for Ceratina. Within a week, you may see pith shavings billowing from stems.

Bee-safe yard: No pesticides, especially on flowers.

Forage Plants (Generalist Pollinators)

Spring: Hepatica, bloodroot, wild geranium, violets, spiderwort, harebell, beardtongue, golden Alexanders
Summer: Butterfly milkweed, tickseed, vervains, black-eyed Susan, common ironweed
Late summer/fall: Stiff goldenrod, any aster

Life Cycle

One generation/year in upper Midwest/Great Lakes/Northeast (C. dupla has two in Canada; two possible in South). Females emerge, mate, seek vertical stems, chew pith to create linear tunnel. Provision bottom, lay egg, use pith shavings for cell dividers. Repeat. Guard entrance against parasitoids.

Overwinter as adults in same stem—another reason to leave stubble. Removing debris may discard your bees.