Forest Preserve District of Cook County, Illinois
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Solitary Wasps and Bees
Nature Bulletin No. 680   May 19, 1962
Forest Preserve District of Cook County 
George W. Dunne, President
Roland F. Eisenbeis, Supt. of Conservation

Our most familiar wasps and bees live in colonies -- the paper wasps, hornets, yellow jackets, bumblebees, and the imported honeybee. These are called social insects because the young and adults live together with a division of labor among the members of a colony.

Surprisingly, these species that live in an organized society are outnumbered -- ten or more to one -- by kinds that lead solitary lives. Among the latter, as a rule, a fertilized female gathers enough food to feed one larva, lays an egg on it, seals it up -- then repeats the process -- but never sees her offspring.

Those fidgety, little, thread-waisted cement workers, the Mud Daubers, which plaster their nests on the underside of roofs and in other sheltered places, are seen more often than other solitary wasps. The female of the most common species seeks the edge of a pool or puddle where she mixes mud and saliva into a pellet of mortar. Making trip after trip, she slowly builds an inch-long tube. Then she hunts spiders. Each one is paralyzed by a sting in the main nerve center and stored in the adobe tube. When the tube is nearly full of helpless but still living spiders, she lays an egg, mixes more cement and seals the door. In this way the wasp larva has a supply of fresh spider meat to eat until it is fully grown.

The female Potter Wasp molds small mud jugs reinforced with hair which she attaches to the twigs of shrubs. Instead of spiders, she stocks her pantry with the paralyzed caterpillars of the cankerworm moth. Of the many other kinds of mud wasps, some use knotholes, keyholes or any small cavity they can find in which they seal an egg with food. The brilliantly colored Cuckoo Wasps, like the cuckoos of the bird world, lay their eggs in the nests of other solitary bees and wasps. Their ravenous offspring devour the food supply of the raided nest and the original young along with it.

The Cicada Killer is the giant among American wasps. In midsummer, after spending their entire lives alone and underground, the black and yellow adults emerge and mate. Now the female selects a spot in sandy or gravelly soil and digs straight down for about a foot, then makes an L-shaped turn and tunnels a few more inches. After the brood chamber is ready, she sets out to search trees for our big "Dog Day" cicada. When one is located, she grabs her prey and tries to sting it in a vital spot. Often in their struggle both plop to the ground and continue the battle until the victim is stung helpless. The cicada is so heavy that she climbs trees or shrubs and often makes several flying take-offs before the burrow is reached. Then the drugged insect is dragged into the nest chamber and, sometimes with one or two more, an egg is laid and the opening closed. The cicada killer, like other solitary bees and wasps, performs its complex routine very exactly and successfully without any previous experience.

Unlike most wasps which store insects and spiders to feed their young, the solitary bees prepare a pabulum of honey and pollen to nourish their infants. Each species seems to have its own particular formula for making this beebread. While gathering this nectar and pollen, a multitude of kinds of bees, both large and small, play a leading role in the cross-pollination of flowers.

Solitary bees always hunt a hidey-hole for a nursery. Most kinds, such as the Sweat Bees, burrow in soil, some use beetle burrows in wood, mud dauber nests or holes in porous rock -- also hollow plant stems, empty snail shells and knotholes.

The Great Carpenter Bee, often mistaken for a bumblebee, chisels long branching tunnels in fence posts and building timbers. At the end of each burrow it seals off a blob of beebread and an egg with a partition of cemented wood chips.

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