BIOLOGY – POLLINATION – FORAGING – DIVERSITY
Bees are flying insects that play a key role in plant pollination. They visit flowers to collect nectar and pollen which they bring back to their nests to feed their young. You’re probably familiar with the common, yellow and black-striped honey bees, and you have probably eaten the honey they make.
Honey bees are not native to the American continent. They were brought to the New World by Europeans and have been managed for honey production and crop pollination for hundreds of years. But not all bees live in large colonies in bee boxes and very few species are managed by humans. In contrast to honey bees, most native bee species are solitary and nest in the ground or in woody stems in the wild. Can you guess how many bee species are in the world? Close to 20,000! And only six species are honey bees.
All bees have the same body type with three segments: head, thorax, and abdomen. The thorax has three pairs of legs and two pairs of wings.
Bees are in the Order Hymenoptera (membranous wings).
Bees have complete metamorphosis with four developmental stages in their life cycle
Bees visit flowers for pollen or nectar and transfer pollen (which sticks to their hair by electrostatic charges) between plants, thus facilitating pollination.
Bees work hard for their pollen and nectar but they share the ‘fruits of their labor’ with us – most fruits, vegetables and nuts we eat are a product of bee pollination. Since 30% of fruit and vegetable crops depend on bee pollination to set fruit, about every third bite we take can be traced back to their nectar or pollen gathering activities.
A balanced breakfast thanks to bees!
Our world without bees…
Bees flight and foraging ranges depend to some extent on their body size which in turn depends on the bee species. Most bees forage in the day but some are active at night. Some of these crepuscular bee species are in the Andrenidae, Colletidae, Apidae and Halictidae families. Their enlarged simple eyes (ocelli) complement their two compound eyes to help them see in dim light.
Bees see in the visible as well as the ultraviolet light spectrum while humans see only in the visible light spectrum. We may just see a colorful flower while bees see nectar guides (patterns and speckles) on the petals!
Flowers seen with visible light (left) and with UV light (right)
What other senses do you think bees use to find nectar? They smell with their antennae like these long-horned bees do!
Generalist bee species visit many plant groups for their pollen while specialist bee species obtain pollen from a narrow group of plants.
Metallic sweat bees and carpenter bees are generalists. A tiny green sweat bee and a large carpenter bee visit peach blossoms in Fredericksburg, Texas. (Photos by Sarah Cusser).
Bumble bees (Bombus spp) shake their abdomens to ‘buzz’ pollen from nightshade flowers in the Solanaceae family.
Cactus bees like Diadasia spp. specialize on prickly pears that many wildlife species eat.
Some celophane bees like Colletes (at top), specialize in wild tomatillo flowers (Solanaceae). Squash bees like Peponapis (bottom) specialize in cucurbits (pumpkin, cucumber, zucchini, gourd).
Many bees are tiny so it’s hard to tell them apart from wasps or flies that visit flowers to feed on nectar. To help distinguish these insects, observe what they’re eating; observe their body shape; and count their wings.
- Bees are herbivores that feed on nectar & pollen and feed them to their larvae.
- Wasps are carnivores that mostly eat insects or spiders and feed them to their larvae, but they consume nectar too.
- Flies are detrivores (eat dead or decaying plants/animals) but often consume nectar. Flies don’t feed their larvae.
Bee, Wasp or Fly?
- Bees and wasps have two pairs of wings while flies have one pair of wings.
- Bees have rounded bodies; wasps have long pointy bodies with small waists.
- Bees have more hair than wasps or flies, and only bees have branched hairs.
- Female bees and wasps sting (there are stingless bees) but flies do not sting.
About 879 native bee species have been described in Texas. In 2012 we studied 10 sites in Central and Northern Texas and found 15 to 39 species per site; 85 species of native bees!
Bees vary in color, shape, and size. They’re as small as a rice grain, medium like a bean, or bigger than popcorn. Hair location is used to categorize bees.
MEET THE FAMILIES …
Within families, bee species have similar morphology, genetics, nesting & feeding biology. Bee families belong to the Apoidea superfamily. Family names end in ~idae.
Digger/miner bees like Diadasia spp (Andrenidae) dig tunnels in the ground for nesting.
The Apidae family contains large carpenter & bumble bees; medium stingless bees, cactus & long-horned bees; and small carpenter bees.
Some Colletidae bees make plaster by chewing leaves into spit balls to line their nests.
Megachilidae leaf-cutters use mega mouth-parts to cut & drag leaves to their nests.
Melittidae bees collect plant oils in dry climates.