The majority (54%) of bees in New York State are digger bees (ground-nesting, solitary bees, such as Andrena, Lasioglossum, Colletes and Melissodes).

Species of Andrena are typical of ground-nesting bees in their life history. At the start of the nesting season (in the spring, summer or fall, depending on the species), female Andrena begin constructing burrows in the soil. At the end of these subterranean burrows they construct brood cells, which are lined with waterproof secretions from the Dufour’s gland. Once a brood cell has been constructed, a female provisions it with a mixture of pollen and nectar collected from flowering plants in the vicinity of the nest.

Foraging ranges in these solitary bees are small – on the order of 500 m maximum – so nests are typically close the floral resources. Once the provisions have been collected, the pollen/nectar mixture is sculpted into a spherical pollen ball and an egg is laid on top. The brood cell is then closed and the female begins constructing a new brood cell. Brood cells range in depth from just a few inches to several feet. A typical solitary female might produce just 10-15 offspring over a period of two to three weeks of active foraging.

While the majority of bees in New York state are ground-nesting, several species also make nests in preexisting cavities, such as twigs, hollow stems, beetle burrows, or in sites above ground. These aboveground, cavity nesters include mason bees, wool carder bees and various resin bees. Mason bees in New York include genera such as Osmia, Hoplitis, Prochelostoma and Heriades.

Mason bees comprise roughly 7% of the species of bees in the state. Other cavity- and stem-nesting bees include the leaf-cutter bees in the genus Megachile, carder bees in the genus Anthidium, Pseudoanthidium and Paranthidium, and the yellow-faced bees in the genus Hylaeus.

Megachile females line their cells with circular pieces of leaf that they cut from rosebushes and other plants. Hylaeus females line their burrows (constructed in plant stems or other hollow tubes) with a cellophane-like material produced by the Dufour’s gland. Hylaeus are unusual bees because they carry pollen internally and not externally, as do most pollen-collecting bees.

Another important group of bees are the carpenter bees. In North America we have both small (Ceratina) and large (Xylocopa) carpenter bees. These bees construct nests in wood or preexisting cavities.

Xylocopa virginica is a common bee in New York. Nests are conspicuous because males hover in front of the nests (typically located in fence posts, wooden park benches and houses) and engage in aggressive territorial battles.

Cleptoparasitic bees comprise 23% of the bee species in New York. The two largest genera of cleptoparasitic bees in New York are Sphecodes and Nomada. Parasitic bees are fascinating creatures. They have lost the morphological structures associated with nest construction and pollen collection in most other bees. Instead of constructing and provisioning their own brood cells, parasitic bees enter the nests of other bees (usually when the host female is away) and lay their eggs within the host nest. Once the host female has laid her egg and closed the cell, the parasitic larva hatches from its own egg and kills either the host egg or young larva, then feeds on the host’s pollen. Parasitic bees have devious methods for hiding their eggs from the host females. For example, Nomada and relatives (in the subfamily Nomadinae) put their eggs in the cell wall of the host bee’s nest.

So far, the vast majority of bees we have mentioned are solitary (or parasitic). Important eusocial bees in New York state include both advanced eusocial taxa in which queens and workers are morphologically distinct (such as Apis mellifera, the introduced honey bee) and primitively eusocial taxa, in which queens and workers are distinguishable from each other based only on size or behavior. Important primitively eusocial taxa include Bombus (bumble bees; Apidae), as well as Augochlorella, Halictus and some species of Lasioglossum (Halictidae). We estimate that approximately 19% of the bee species in New York are eusocial.