Wasps vs. Bees

by Jaime Pawelek and Rollin Coville

Wasps are the insects that most people can relate to seeing at their picnics, especially yellow jackets. While they can be irritating at times, they do serve an important ecological function. They are predators of many insects, especially crop eating insects. Parasitic wasps are beneficial because they can be released into agricultural systems and they serve as natural biocontrol of insect pest populations. They lay their eggs on or inside their host and as the wasp develops it feeds on its’ host. The hosts are usually what we consider to be garden pests like: tomato hornworms, aphids, cabbage worms, armyworms, and strawberry leaf rollers. After the parasitic wasp completes development it emerges as an adult and kills the host.

Wasps also serve as food for many other species, like birds, and thus contribute to the food chain. Also, because some species visit flowers for nectar they can be inadvertent pollinators. There are hundreds of species of wasps in California, and like bees they are part of the heritage of the land. In the San Francisco Bay Area some of the most common wasps are: yellow-jackets, paper wasps, mud daubers, sand wasps, thread-waisted wasps, and potter wasps.

Wasps and bees are often mistaken for each other, but knowing a few key features of both can help one tell them apart. Bees gather pollen and nectar from flowers to use as food for their offspring. Wasps are carnivorous and hunt for other insects or spiders, but some also visit flowers for nectar. Bees usually have very hairy bodies and pollen collecting hairs on their legs or under their abdomen to help them accomplish this task. Wasps tend to have few to no hairs at all because they don’t intentionally collect pollen.

Some bees look like wasps because they don’t have much hair on their bodies. They collect pollen and store it internally in their crop instead of on the outside of their bodies. Some other relatively hairless bees, cuckoo bees, don’t collect pollen because they lay their eggs in the nests of other bees. Wasps usually have more elongate bodies, longer legs, and sometimes have what looks like a pinched waist, whereas bees usually look more compact. There are other physical differences between bees and wasps, but they are hard to make out without the use of a hand lens or microscope. So, if you see a busy creature flying from flower to flower and actively collecting brightly colored pollen, then you can be fairly sure it is a bee.

Bees actually evolved from predatory wasps (apoid wasps), so bees and wasps have a lot of similarities both in appearance and behavior. Bees and wasps both have two sets of wings, unlike flies, which only have one. Also, only the females of bees and wasps can sting because the stinger is actually a modified egg laying apparatus. Behaviorally they are similar in that they both have social and solitary species. Yellow jackets, like bumble bees, have seasonal colonies that form in the spring and die out in the late fall with the queens overwintering to start a new colony the following year. The majority of bees and wasps though are solitary, and the female does all the work of building and provisioning nests for her young.

One wasp that a lot of people confuse with bees is the yellow jacket. Unlike honey bees, yellow jackets and other wasps don’t leave their stinger behind when they sting something, therefore they are able to sting several times in a row. These social wasps form papery nests both above and below ground that can contain anywhere from 50 to 5,000 individuals. The larger the colony gets the more aggressive the wasps become. This usually happens in late summer/early fall when food is in short supply. Yellow jackets then become nuisances at picnics eating whatever they can find. The adults will sting and paralyze insect prey as well as scavenge from carrion to provide as food for their offspring. As adults they mostly feed on nectar, honey dew, and rotting fruit.

Here's a table to help you tell the bees from the wasps in your garden (All photos courtesy of Rollin Coville):

Bees	Bees that may be confused with Wasps	Wasps
A common long-horned bee, Svastra obliqa expurgata, from Sacramento, CA. Notice the pollen on the hind legs.	A cuckoo bee, Nomada sp., from Berkeley, CA. Nomada are frequently associated with nests of ground nesting bees in the genus Andrena.	A yellow jacket wasp, Vespula sp., from Berkeley, CA. Watch out for these social wasps at picnics.
A carpenter bee, Xylocopa sp., robbing a flower of nectar from Sacramento, CA. Carpenter bees are our largest bees.	Some cuckoo bees in the genus Nomada are black with yellow markings. This female is monitoring a nest of Andrena transnigra in Sierra Co., CA.	Bembix americana comata is a sand wasp that commonly visits flowers for nectar. Bembix are solitary wasps that can be mistaken for bees, but they are actually predatory. They hunt flies, which they use to provision their larval cells.
A female of Megachile perihirta on a Gaillardia flower head from Berkeley, CA. Note that this leaf-cutting bee collects pollen on the underside of the abdomen.	A female of a small carpenter bee, Ceratina acantha, from El Cerrito, CA. These small bees excavate their burrows in the pith of broken stems such as those of elderberry, mustard, and black berries.	Mischocyttarus flavitarsis is a common paper wasp in California. Another genus, Polistes, make similar but often much larger nests.
A small sweat bee, Halictus tripartitus, in a California poppy. Note the pollen on the upper leg and base of the abdomen.	Sphecodes are sweat bees that have become cuckoos. They are small bees that are usually black with a red abdomen, although males of some may be entirely black. Their hosts are usually other sweat bees.	A male bee wolf, Philanthus zebratus. Philanthus are frequent flower visitors. These are solitary wasps. Females hunt bees and sometimes wasps, hence the name bee wolf. They use the prey to provision their larval cells.
A male bumble bee, Bombus melanopygus, dinking nectar from a seaside daisy in San Francisco.	A male wool carder bee, Anthidium sp., from Sacramento, CA. We have nicknamed this the head-bonker bee because of its aggressive territorial behavior.	A potter wasp gathering mud that it will use in building its nest in Berkeley, CA. These wasps are solitary relatives of the social yellow jackets, paper wasps, and hornets. Potter wasps provision their larval cells with caterpillars.
A mining bee, Anthophora edwardsii, spading moist earth over the entrance to her completed nest in El Cerrito, CA. This bee carries water that it regurgitates to soften the soil.	Masked bees, genus Hylaeus, such as this one from Berkeley, CA, are very small bees that carry pollen and nectar internally. They have few body hairs and usually have black and yellow markings, which give them a strong resemblance to small wasps.	Spider wasps, family Pompilidae, sometimes visit flowers for nectar. Most Spider wasps are a dark metallic blue black, although some, such as this one, exhibit other color patterns. These wasps are extremely quick and agile.