Nomada imbricata

Nomada imbricata can be distinguished from other Nomada species by its imbricate integument pattern and specific coloration. As with all Nomada, it lacks the dense branched hairs characteristic of pollen-collecting bees, instead presenting a relatively smooth, wasp-like appearance. Accurate identification to species level typically requires examination of morphological details including genitalia and specific pattern elements. The species may be confused with other Nomada species, particularly those with similar color patterns in the same geographic region.

Nomada imbricata exhibits the typical wasp-like appearance of cuckoo bees, with reduced body hair compared to pollen-collecting bees. The species has short, sparse hairs that form distinct color patterns, typically incorporating black, white, red, and yellow. The integument shows an imbricate (overlapping scale-like) pattern that gives the species its common name. Body size falls within the range typical for Nomada species, approximately 5–10 mm in length. The mandibular glands of males produce chemical compounds.

Nomada imbricata is associated with habitats where its host bee species occur. As a kleptoparasite of ground-nesting Andrena bees, it requires areas with suitable bare ground or soil substrates for host nesting. The species has been documented in Vermont, suggesting occurrence in temperate North American habitats including open woodlands, meadows, and other areas supporting diverse bee communities.

North America, with confirmed records from Vermont, United States. The species' range within North America is not fully documented but appears to be centered in the northeastern United States.

Activity patterns follow those of its host species, with adults typically active during the spring and summer months when Andrena hosts are nesting. Specific flight period data for N. imbricata is limited.

• Andrena - kleptoparasiteNomada imbricata is a nest parasite of Andrena mining bees. Females enter host nests to lay eggs in provisioned cells; the developing Nomada larva consumes the host egg or larva and the stored pollen provision.

Nomada imbricata exhibits the typical cleptoparasitic life cycle of the genus. Females locate host nests of Andrena species, often using olfactory cues including floral oil scents. They enter unguarded nests and lay eggs in provisioned cells. The Nomada larva hatches before the host larva, kills the host egg or young larva, and consumes the pollen and nectar provision. Development proceeds with the parasitic larva using the host's stored resources. The species likely has a univoltine or bivoltine cycle depending on host phenology, with adults emerging to mate and seek host nests.

Males have been observed to patrol areas where host bees are active, including flowers such as willow and gooseberry. Male Nomada exhibit "antennal grabbing" behavior during copulation, winding their antennae around the female's antennae to transfer pheromones. This behavior, first documented in the genus Nomada in 2018, may serve to transfer chemical compounds that help females mimic host bee odors for nest entry, or may function to make females unattractive to rival males. Males also deposit pheromones on vegetation by rubbing their bodies against grass to mark mating territories.

As a kleptoparasite, Nomada imbricata functions as a natural population regulator of its host bee species. Cuckoo bees contribute to bee community dynamics and may influence host nesting behavior and distribution. The species participates in pollination networks indirectly through its association with host foraging activities, though it does not actively collect pollen.

Nomada imbricata has limited direct human relevance. As with many native bees, it contributes to overall pollinator diversity and ecosystem health. The species may serve as an indicator of healthy bee communities and intact habitat mosaics supporting ground-nesting bees. It has no known agricultural or economic significance.

• Nomada flavoguttataShares similar color pattern elements and geographic range; both are North American Nomada species with yellow markings. Distinguished by specific pattern details and integument texture.
• Other Nomada speciesMany Nomada species exhibit similar wasp-like appearance with black, yellow, red, and white patterns. Accurate identification requires detailed morphological examination, particularly of male genitalia and specific integument patterns.
• Andrena host speciesMay be confused with host bees when observed quickly, but Andrena have dense branched body hairs for pollen collection, while Nomada imbricata has sparse, short, unbranched hairs giving a smoother appearance.

• cuckoo bee
• kleptoparasite
• cleptoparasite
• Apidae
• Nomadinae
• Andrena parasite
• North America
• ground-nesting bee associate

• BugGuide
• GBIF taxonomy match
• iNaturalist taxon
• NCBI Taxonomy
• Catalogue of Life
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