Page content: Laurel Treviño, UT Austin and Assist. Prof. Margarita López Uribe, PhD, Entomology Penn State. You may print the Jha Lab’s educational material (by L. Treviño, hyperlinked) for educational and conservation purposes. Photo copyrights apply to page photos, credits at end. Questions? L.Treviño, Jha Lab Outreach Coord. (info bottom of page)
Out of 20,000+ bee species that have been described worldwide, approximately 4,000 inhabit North America (Northern Mexico, U.S., and Canada). Western honey bees were brought to the American continent in the 1600’s by Europeans who managed apiaries for honey, wax, and mead production. Tropical American civilizations had been harvesting honey from some of the six honey-producing native bee species. (Native bee and Apis mellifera. Photo: Kathy Keatley Garvey, The University of California Regents).
Beyond honey and wax, bees provide pollination services on farms and orchards and pollinate ~87% of wild plants. Bees are key pollinators that visit flowers for nectar and pollen and facilitate pollination by consistently transferring pollen between plants of the same species (floral fidelity). ~30% of fruit, vegetable and nut crop species rely on all pollinators to some extent to set fruit. That means, every third morsel of the food in our diets comes from pollination activities. Bees work hard to collect nectar and pollen for food, but they share the fruits of their labor with us, literally…
A drab world without bees…
A balanced breakfast thanks to bees & other pollinators!
Foraging bees travel far beyond their nesting habitat to look for food. Flight ranges depend to some extent on body size, which in turn depends on the bee species. Bees can fly from 500 meters to a kilometer away from their nest, but some tiny tropical bees can fly up to 2 kilometers (1.25 miles) to gather pollen! Bees agility lets them reach the hidden anthers of bluebonnet and sage flowers by standing on the keel to open up the flower.
green sweat bee (discoverlife.org); squash bees (T’ai H. Roulston); bumble bee (Charles Schurch Lewallen)
Most bees forage and feed by day but crepuscular bees can see in dim light at dusk and dawn. Three tiny ‘simple eyes’ on a bee’s head see shades of gray while two large compound eyes see color. Do you see 3 ocelli on the sweat bee’s head? Bees can see in visible and ultraviolet light spectrums, while humans see only visible light. While we see a plain yellow flower (left), bees see nectar guides on blue petals! The flower on the right is seen in UV light. In their quest for food, bees are attracted to colorful aromatic flowers by sight (eyes) and smell (antennae). Look at the ‘long-horned’ bee’s antennae!
(Halictus poeyi, USGS Native Bee Inventory Monitoring Lab) (Sam Droege)
Generalist bees obtain pollen from many plant groups. Bumble bees, which tend to be generalists, can shake the pollen from flowers by clinging to the anthers and shaking their body, which produces a buzzing sound, sonication, on a C note. Most bees are generalists.
Specialist bees tend to obtain pollen from a narrow group of plants (a species, genus or family), unless environmental stressors change their feeding habits. Squash bees prefer squash flowers, while cactus bees prefer prickly pear cactus, and sunflower bees prefer…:)
Nesting females make and provision nests. They subdivide cavities into compartments where they lay a single egg in each cell. They usually seal the nest with leaves or mud or plug the hole with their own body! Native bees can nest in wild-lands, orchards, farms or gardens. North American native bees are ~70% ground-nesters and ~30% cavity-nesters.
Ground Nesting (pdf) bees dig holes with their front legs and mouth. They can make tunnels more than a foot deep. Sweat bees and digger bees make level entrances, while sunflower bees build chimney turrets. Bumble bees can nest on the ground under grass thatch, while other bees must dig deep underground to reach a more stable micro-environment. After smoothing the walls with their underbelly, ‘cellophane’ bees apply secretions with their tongue for a waterproof lining.
Cavity Nesting (pdf) bees can use their mouth parts to carve holes in soft wood or retrofit rock crevices. Leaf-cutter bees line and partition cavities with pieces of leaves or flowers (top left, Kathy Keatley Garvey, UC). Mason bees chew mud to plaster and plug holes with the mastic (top right, Scott Famous). Small carpenter bees carve holes in the pith of plant stems (bottom left, Alain C.), while large carpenter bees drill horizontal tunnels through soft wood (bottom right, Sean McCann).
Watch leaf-cutter bees making nests inside bamboo cavities!
Sociality is defined mostly by nesting habits. 90% of native bees are solitary, that is, a single female makes and provisions her nest. Solitary bees can aggregate nests in one area but they each stock their own nest with food. Females may also share a common entrance while each one provides for her own larvae in their cells. In semi-social bees, like bumble bees, individuals of the same age (cohort) divide the labor, foraging and caring for young sisters in annual colonies. Social tropical bees form communal nests from Central Mexico to South America where females feed nectar and pollen to their developing young. Native bees generally lay few eggs, so the larvae survival rates and adult population size shift seasonally depending on resources and disturbances.
Bee life cycles involve complete metamorphosis (jpg) with four developmental stages: egg, larva, pupa, and adult. Females lay an egg on pollen loaves or near liquid food they prepare for developing larvae to eat during their weeks-long development. Adult bees can live about a month (mason, mining bee), a year (bumble bee), or three years (large carpenter, western honey bee) depending on the species and sex.
Egg & larva on pollen balls (Dennis Briggs)
Pupa in ground brood cell (Robbin Thorp)
Adult mining bee (John Ascher)
To conserve native bees we must protect habitat for young and adult bees year round. Natural bee habitat includes patches of bare ground, rock or wood cavities and thatch for nesting. For ground-nesters, protect soil from erosion and don’t compact mud with heavy machinery. For cavity-nesters, leave snags, fallen tree logs, and grass thatch. Do land stewardship and gardening activities before bees emerge from their nests in early spring. To ensure bee food sources, augment locally adapted, native plants like wildflowers and bunch-grasses. Spring blooms (herbs and trees) feed hungry bees, asters maintain bee populations through hot summers, and fall blossoms help females provision their nests. Diverse and healthy bee populations depend on diverse and abundant plant communities.
Native plants are essential for bee larvae who digest their pollen readily. Native bees prefer native flowers to non-native ones. Bee life cycles are synchronized with native plants that flower during bee foraging seasons. If you use local native plants in your landscape, native pollinators will find them!
Here’s our top ten list of Texas Prairie Plants for Native Bees.
A more comprehensive list of native pollinator plants is provided by The Lady Bird Johnson Wildflower Center: www.wildflower.org/project/pollinator-conservation
Woodlands and prairies at the UT Brackenridge Field Lab, sustain more than 200 native pollinator species on 80 acres. Here are the most common pollinators at BFL(.pdf)
Native bees thrive in open prairies, mixed woodlands, farms and gardens where constellations of native plants flower in a succession of colors. To help conserve and monitor pollinator habitat, see Naturalists|Citizen Scientists.
How Do You ID a Bee?
Like all insects, a bee’s body has three regions: head, thorax, and abdomen. The thorax has three pairs of legs and two pairs of membranous wings (a trait of the Order Hymenoptera). The segmented abdomen may have colored bands, and branched hair covers some or all of their body.
Many bees are tiny and look like wasps or flies. To distinguish them, observe their shape, hair, wings, and what they eat!
Bee, Wasp or Fly?
- Bees are mostly herbivores; they eat only nectar and pollen from flowers
- Wasps are carnivores; they mostly eat insects but also drink nectar from flowers
- Flies are mostly detrivores; they eat decaying plants or animals but also blood or nectar
- Bees/wasps: 4 wings, long elbowed antennae. Flies: 2 wings, stubby straight antennae
- Bees/flies have rounded bodies; wasps have long narrow bodies with pointy abdomens
- Bees are hairier than wasps or flies and only bees have branched hairs that carry pollen
Out of 4,000 bee species native to North America, more than 800 have been identified in Texas. The Jha Lab has studied pollinators from 60+ sites in Texas. Meet the six bee families in Texas and the American continent.
Bees are smaller than rice grains, the size of pinto beans, or bigger than almonds. Color and ‘hair’ location are used to identify bees, which can be very colorful!
- (Apidae) Bumble bees, large & small carpenters, stingless, cactus, long-horned bees
- Plasterer bees (Colletidae) chew leaves or mud into spit balls to line their nests
- Miner bees (Andrenidae) dig underground tunnels with a chimney entrance
- Sweat bees (Halictidae) are mostly tiny with a metallic sheen; they lick sweat for salt
- Oil-collector bees (Melittidae) collect plant oils in dry climates
- Leaf-cutters (Megachilidae) use mega mouth-parts to cut & carry leaves to their nest
Can you recognize native bees in your Central Texas garden?