Pike County's Cuckoo Bees

In contrast, North American cuckoo bees keep a low profile. Their existence helps to control other bee species’ populations. Working on their own, these little bees accomplish this goal.

The balance of life on our planet is interwoven, rhythmic and, for the most part, sustainable. Seven hundred cuckoo bee species live in various parts of our world. At least 300 species live in North America alone. These habitat specialists make up 20 percent of all bees in North America. That is one in five. They belong to the largest bee family, Family Apidae.

This group’s key players include bumble bees, carpenter bees, cuckoo bees, honey bees, orchid bees, and stingless bees. Narrowing down their classification further, cuckoo bees are in Genus Nomada. Nomada derives from the Greek word nomas meaning “roaming” or “wandering”. Those words fit them well.

These bees do not look like typical bees. Cuckoo bees lack the pollen-carrying scopa, a defining mark of most bees. They are missing this thick mass of long hairs on their hind legs. Long-horned bees, mining bees, and sweat bees have scopa on their legs. Mason and leafcutter bees’ scopae reside under their abdomens. This body part is different from a honey bee’s hind leg pollen baskets (corbiculae). Bumblebees, stingless bees, and orchid bees have corbiculae too.

A cuckoo bee’s prevailing overall color is commonly red, black, or yellow. Many have red legs. Their wings or wing tips are dark and tinged with brown or black. The lack of a scopa, overall color, and mostly hairless body makes them look more like wasps than bees. Their life cycle tells the story of their purpose in life.

Like the European cuckoo birds, cuckoo bees lay their eggs in a host’s nest. They never build their own. Neither do they collect pollen. They do not have the proper apparatus. There really is no need as these kleptoparasites use the nests of host bees and the provided pollen. At least some male Nomada release the same chemical that host bees do. They transfer the chemical by intertwining antennae with females during mating. This disguise makes the female Nomada smell like the host as she steals into its nest.

Visual clues help these nomads locate host nest entrances. Females fly low over the ground. Once she bee finds the nest, female Nomada uses her sense of smell in many ways. She determines whether the nest has pollen. She finds out if the host bee is present. She deduces whether parasitism has already occurred. She notices if other parasitic bees are in the area.

Only if all is well does the female enter the nest and lay one to four eggs in the prepared cell wall. She oviposits or lays eggs before the host does. In using the resources the host has already collected, the cuckoo bee’s offspring will consume the supplied food that the host left for its own larva. When the host lays her egg in that cell, she afterwards seals off that nest cell.

All bees go through complete metamorphosis (egg, larva, pupa, adult). Nomada young come out of their eggs a little sooner than host larva. Once the first cuckoo bee egg hatches, this parasitic larva uses its scythe-like mandibles (mouthparts) to kill host offspring as well as its sibling offspring. In this cell, the early larva gets the pollen.

The larva feeds on the provided pollen. It then pupates in the host cell and emerges as an adult the following season along with the unparasitized host’s offspring in other cells, the survivors. Adults fly to flowers to feed on their nectar and repeat the life cycle.

Cuckoo bees parasitize many types of ground-nesting bees. They follow “Emery’s rule” stating that social parasites tend to be a sister species or close relative of the host. Our mining bees, Genus Andrena, are their main targets. They also go after Agapostemon (metallic green sweat bees), Eucera (long-horned bees), and Halictidea (sweat bees), all found in the Pike County survey. Besides these, they single out Melitta and Exomalopsis; neither live here. These bees are small, 5/16- to 3/8-inches in length. Their flight season and geographic range coincide with their hosts’. They show extreme variation in appearance and conduct from one species to the next.

Cuckoo bees live in Pike County. Their existence depends on other bee species for habitat and larval sustenance. These bees are a natural part of our ecosystem. They are not a threat to the pollinator population. Masquerading as wasps, they live their lives and have purpose. These stealthy copycats keep other bee species in check. We need them, perhaps more than we know.

To paraphrase Charles Caleb Colton’s well known 1820 phrase, parasitism is the sincerest form of flattery.

Family Apidae, Genus Nomada (found in Pike County 2020 Survey): (Four bees found; this group includes cuckoo, carpenter, digger, bumble, & honey bees.)

To contact guest columnist Rebecca Thomas, she can be reached by email at rebeccathomas123@yahoo.com.