California Native Plant Society
in collaboration with East Bay Municipal Utility District
Wasps
All writing from May Chen's posts
American Sand Wasp-
Bembix americana (family Crabronidae)
The most conspicuous insects are the large American Sand Wasps, Bembix americana (family Crabronidae). The wasps are chasing each other in flight over the bush, only occasionally landing to refuel on flower nectar.
Sand wasps in the genus Bembix are familiar and common throughout North America, digging their burrows in dunes, on beaches, and other habitats with loose, deep sand. The female rapidly kicks out large quantities of sand using a “tarsal rake” of spines on each front leg. The burrow is excavated before the wasp goes hunting. Bembix are generalist, opportunistic hunters. True flies in the order Diptera are the usual prey. A victim is paralyzed or killed by the wasp’s sting, and is then flown back to the nest. Most species will lay an egg on the first victim, while some species lay an egg in the empty cell before starting to hunt. Once the egg hatches, mama wasp brings flies to her larva as needed. This “progressive provisioning” is rare in the insect world. When the larva reaches maturity, mama wasp closes the cell. Inside, the larva spins an oblong cocoon, weaving sand grains into the structure and resulting in a hardened capsule. Overwintering takes place as a prepupa inside this cocoon, but there are usually two generations a year.
Male sand wasps often engage in an elaborate flight ritual called “sun dances”. Males emerge before females, and fly erratically at dizzying speed one or two inches above the ground attempting to detect virgin females about to emerge from their underground nests. Both sexes are often seen taking nectar at flowers, especially from Asteraceae family. Bembix wasps are often victims of other insects such as cuckoo wasps (Chrysididae), velvet ants (Mutillidae), satellite flies (Sarcophagidae), bee flies (Bombyliidae), and thick-headed flies (Conopidae).
Common Aerial Yellowjacket-
Dolichovespula arenaria
Dolichovespula arenaria, also known as the Common Aerial Yellowjacket, is widely distributed in the North American continent, commonly found in forested areas. They are important pollinators that contribute to the production of certain fruits. They transfer pollen as they forage for nectar. The wasp can also be a biological control agent as it helps to reduce populations of pests that damage crops.
Like the other yellowjackets, the D. arenaria is eusocial, meaning it lives in a colony with a division of labor and cooperative care of the young. The colony consists of a queen, who is the only fertile female, and workers, who are sterile females. The queen has the ability to control the sex of the offspring through haplodiploid sex determination, laying fertilized or unfertilized eggs. Early in the season she typically produces female workers who help build the nest and forage for food. As winter approaches, she starts to produce males and future queens. The queens overwinter.
The Aerial Yellowjackets builds their nests by transforming chewed wood into a paper-like substance, which is why they are considered paper wasps. The nests are usually located above the ground, on trees, shrubs, or buildings, hence the name “aerial”.
Mason Wasp-
Ancistrocerus bustamente (family Vespidae, subfamily Eumeninae)
A Mason Wasp, Ancistrocerus bustamente (family Vespidae, subfamily Eumeninae) makes frequent stops at the Coffeeberry flowers, but I only manage to capture a picture as it lands for a split second on a leaf.
Potter wasps (or mason wasps), the Eumeninae, are a cosmopolitan wasp group presently treated as a subfamily of Vespidae. Most eumenine species are black or brown, and commonly marked with strikingly contrasting patterns of yellow, white, orange, or red. Their wings are folded longitudinally at rest. Eumenine wasps are diverse in nest building. The Mason Wasps are species that generally nest in pre-existing cavities in wood, rock, or other substrate. Potter Wasps are the species that build free-standing nests out of mud, often with a spherical mud envelope. The most widely used building material is mud made of a mixture of soil and regurgitated water.
All known Eumenine species are predators, most of them solitary mass provisioners. When a cell is completed, the adult wasp typically collects beetle larvae, spiders, or caterpillars and, paralyzing them, places them in the cell to serve as food for a single wasp larva. As a normal rule, the adult wasp lays a single egg in the empty cell before provisioning it. The complete life cycle may last from a few weeks to more than a year from the egg until the adult emerges. Adult mason wasps feed on floral nectar.
Mason Wasp-
Euodynerus annulus (family Vespidae, subfamily Eumininae)
The Mason Wasp, Euodynerus annulus (family Vespidae, subfamily Eumininae) is a widespread species, found from coast to coast in the United States, south to Mexico, and north into Canada. The color and markings vary considerably among the various subspecies. These are sizable wasps, their fore wings measuring 8.5-10.5 mm. Males can be recognized by the hooked tips of the antennae, and their less robust appearance. Unlike the other Mason Wasps that use pre-existing cavities, or making mud nests, the females of this species excavate burrows. They also extend the tunnel above ground as a curved mud “chimney”. Several individual cells branch from the main burrow underground. The species seem to favor situations close to water, as the female regurgitate water to soften the soil during nest-building. The chimney might help protect against parasites, but it apparently serves as the source of mud pellets to make the final nest closure as well. Eventually, the turret is deconstructed entirely and the nest entrance made nearly invisible and flush with the surrounding soil.
The female wasps provision their nests with moth caterpillars as food for their offspring. A single egg is suspended from a short thread attached to the wall of the cell before it is stocked with caterpillars. Usually several caterpillars are placed in each cell. When all cells are provisioned, the nest entrance is sealed. The turret or chimney is deconstructed entirely and the nest entrance made nearly invisible and flush with the surrounding soil. The wasp leaves to begin a new nest.
Great Black Digger Wasp-
Sphex pensylvanicus (family Sphecidae)
The Great Black Digger Wasps occur across most of the United States, and grow to a size of 0.8-1.4 in. They can commonly be found patrolling flowering plants during the summer. The adults drink nectar from flowers while hunting for prey items for their young.
Like other digger wasps, the Great Black Digger Wasp females build their nests in the ground. The female digs about a foot beneath the soil and creates a series of tunnels using her mouth and spiny legs. The adult females are active hunters that paralyze and carry their prey back to the nest for their brood. Their prey consists of many insects in the Orthoptera order (crickets, katydids, and grasshoppers). Prey are stung three times - once in the neck and twice in the thorax. Although paralyzed, the prey can survive for weeks. The female places a prey insect in each chamber. She then glues an egg to the underside of the prey insect between the first and second pairs of legs. Each of the several chambers in the nest houses a single larva, which consumes 2-6 katydids or grasshoppers. When a brood tunnel is eventually filled up with developing young, a female will seal off the chamber to protect the larvae from parasites or thieves coming to steal her young’s food. To do this, she will often use her head and vibrate her abdomen to tamp down the soil but may also use small tools like a pebble or piece of stick. The larvae will slowly eat away at the prey’s paralyzed body over the course of a week while it is still alive. The larvae pupate and overwinter in their burrows until the following summer when the cycle begins all over again.