Sphecodes

Sphecodes are parasitic halictids of variable size. Both males and females are typically black, almost completely hairless and with a partially or totally red abdomen that superficially resembles some sawflies or ichneumonids wasp. Identification can be challenging, and, in the case of the males, often requires the genitalia to be visible. They are cuckoo bees that attack ground nesting species, including other halictids such as Lasioglossum and Halictus. Females are known to access the nests of the host and destroy their offspring, sometimes killing the mother in the process. After doing so, they lay their own eggs inside the nest and close the entrance. These eggs hatch within the same year, resulting in a new generation of adults that appear by the end of the season. However, only fertilized females overwinter to re-start the cycle.