The Planters' Guild · A Pillar of the Guild
The creatures that close the loop. A field guide to sixteen Bay Area pollinators and the flowers their bodies fit.
Most pollinator writing starts with the bee. We start with the relationship.
Plants and their pollinators have co-evolved features that make them likely to meet, and those features, known as pollination syndromes, can be used to predict the kind of pollinator likely to visit a flower (USDA Forest Service). Butterflies, for instance, tend to favor flat, clustered flowers that give them somewhere to land, while hummingbirds work tubular flowers with their long, slender bills (USDA Forest Service).
The Pollinator Library covers sixteen pollinators you can meet around the Bay Area, one per entry: what it looks like, how to tell male from female, where it lives, and the flowers its body fits. We chose them by how often people record them here, not by whether they are native, and each entry says plainly which are native and which arrived from elsewhere. The shelf reads in order: flies and bees first, then butterflies, a moth, and the only bird on the shelf, Anna's hummingbird.
The Hover Fly
Allograpta obliqua
A small fly, about a quarter inch (6 to 7 mm) long, striped and banded in yellow, that can hover and even fly backward. Like other flies, it has a single pair of wings, where bees and wasps have two, and its larvae hunt aphids.
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The Honey Bee
Apis mellifera
There were no honey bees in North America until European colonists brought them; the first known introduction to what is now the United States was at Jamestown, Virginia, in 1622. Workers carry pollen home in a basket on each hind leg, and, unlike bumble bees, they don't buzz-pollinate.
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The Sweat Bee
Halictus tripartitus & H. ligatus
Bees with pale bands of hair across the abdomen: H. tripartitus has a dull metallic green thorax, while the female H. ligatus is black. Like most Halictus, they visit many kinds of flowers, nest in the ground, and are very common on daisy-like flowers in summer and fall.
The Wool Carder Bee
Anthidium manicatum
Its bright yellow markings can pass for a yellowjacket's, but it is hairier and stouter; first recorded in North America in 1963, it was detected in California in 2007. Females scrape the woolly hairs off plants such as lamb's ear to line their nests, and the males, unusually for bees, are larger than the females and guard their favorite plants.
The Leafcutter Bee
Megachile perihirta
Leafcutter bees line their nests with rounded pieces cut from leaves, and carry pollen on hairs under the abdomen rather than on the hind legs. This species, Megachile perihirta, nests in the ground.
The Bumble Bee
Bombus vosnesenskii & B. melanopygus
The yellow-faced bumble bee is mostly black, with a yellow face, yellow at the front of the thorax and one yellow band near the tail; the black-tailed bumble bee's dark form is the one found mainly in California. Bumble bees can buzz-pollinate, vibrating a flower such as a tomato's until the pollen shakes loose.
The Carpenter Bee
Xylocopa sonorina & X. tabaniformis
A glossy, almost hairless upper abdomen sets carpenter bees apart from bumble bees; valley carpenter bee males are golden with green eyes, and the females are dark. Females chew nest tunnels in untreated wood such as fence posts, and when a flower is too deep for their tongues, they sometimes cut a slit at its base to reach the nectar.
The Painted Lady
Vanessa cardui
A migrant: from the deserts of northern Mexico it spreads north and settles, for a season, across much of the United States and Canada. Its caterpillars have been recorded on more than 100 plants, with thistles and mallows among the favorites.
The Cabbage White
Pieris rapae
Introduced from Europe; its first North American record is from Quebec City, in 1860. Its caterpillars feed on the mustard family, cabbage, broccoli and kale among them, and the adults turn up in gardens, along roadsides and in cities and suburbs.
The Fiery Skipper
Hylephila phyleus
A skipper with permanent populations across most of low-elevation California. Its caterpillars feed on grasses, often Bermuda grass, and the males perch in lawns waiting for females.
The Gulf Fritillary
Agraulis vanillae
The underside is brown, with long, iridescent silver spots on both wings. Its caterpillars feed on passionvines.
The Anise Swallowtail
Papilio zelicaon
A western swallowtail, ranging from British Columbia south through California to Baja California and Mexico. Its caterpillars feed on the parsley family and some citrus; in California's lowlands they use sweet fennel almost exclusively, along with orange trees, both brought by Spanish missionaries in the 18th century.
The Western Tiger Swallowtail
Papilio rutulus
Large and yellow, with thin black stripes across the forewing and a long tail. Its caterpillars feed on broad-leaved trees, cottonwoods, some willows and western sycamore among them.
The Monarch
Danaus plexippus
Adults sip nectar from many flowers, but eggs and caterpillars are found only on milkweeds. Western monarchs migrate to spend the winter on the California coast.
The White-Lined Sphinx Moth
Hyles lineata
It usually flies at dusk, through the night and at dawn, but also by day, and it hovers in front of tubular flowers to drink through a long proboscis. By day it visits brightly colored flowers; in the evening it favors white or pale ones.
Anna's Hummingbird
Calypte anna
The male's rose iridescence covers both his throat and his crown; a female may show only a few streaks of color at the throat. It can be found year-round along the West Coast, drinking nectar and also eating small insects and spiders.
Bookmark this page to follow along as entries go live. Spotted something on a flower and want a name for it? Start with the plate that looks closest, then check the field marks in its entry.