Eucera is a genus of bees in the family Apidae, which comprises more than 100 species. These bees are commonly known as long-horned bees due to their characteristically long antennae, especially in males. Eucera species can be found in diverse habitats, including meadows, fields, and urban gardens, primarily in the Palearctic and Nearctic regions, covering parts of Europe, Asia, North Africa, and North America.
Eucera bees play a crucial role in pollinating a wide range of flowering plants. They are solitary bees, meaning that each female builds and provisions her own nest without forming social colonies like honeybees. Female Eucera bees construct their nests in the ground, typically in well-drained, sandy soils. They lay their eggs within the nest and provide a food supply for their offspring by collecting pollen and nectar from flowers.
Eucera bees are active from spring to fall, and their flight period often coincides with the blooming period of their preferred flowering plants. They are generalist pollinators, meaning they visit a wide variety of flowers, but some species show preferences for specific plants or families, such as legumes or sunflowers.
Eucera kullenbergi is known to fall victim to sexual deception by Ophrys leochroma flowers that mimic the sex pheromones of female bees. Eucera palaestinae live in dense nest aggregations with males emerging from their nests in the ground about a week before the females to take a look around the nesting site. Once the females emerge, males of the species will engage in aggressive competition to mate with them. Shortly after mating, the female becomes unreceptive. The initial attraction towards a female is by sight, but there is additional research suggesting that virgin females are distinguished by their specific scent and therefore are sought after more aggressively. It is thought that the cause of this sex attraction is due to small glands located on tergites on the abdomen. In Eucera nigrilabris, the males also emerge a few days earlier than females. Once the female emerges from the nest, males will fight with each other to mate. Mating time in this species occurs for 3–6 minutes, and once the female has mated, she becomes unresponsive.
Eucera can be generalists or specialists in foraging preference. They are able to pollinate both agricultural and naturally occurring plants. They pollinate plants in the deserts of Israel and the Mediterranean. Eucera, like other efficient foragers, avoid going back to the same food source after it has been previously depleted. Research suggests that Eucera use a combination of reward-based-patch-leaving rule and scent marking strategy to avoid returning to previously visited sites. Eucera resemble bumblebees in this matter but it is believed that they use different strategies (bumblebees use a numerical strategy) suggesting that the difference in strategies may reflect the lower learning capabilities of solitary bees like Eucera when compared to the social bumblebee. Eucera cinerea has specialized thick bristles that curve and are used for foraging for pollen within flowers that have hidden anthers. Eucera from southwest France are known to mainly forage from Fabaceae and Brassicaceae plants. Peponapis and Xenoglossa are known to be specialists for squash plants, such as Cucurbita pepo. Peponapis pruinosa specializes on squash plants, and so the current distribution of this species in North America is due to the expansion of plant cultivation throughout North America. The species moved from Mesoamerica into the more temperate regions of North America.
