Here it is, 7 November, and the honey bees were still busily working over the Brazilian sage, lantana and chrysanthemums in my garden. The Eastern carpenter bees were absent today, perhaps because of the cold night we had, but a few butterflies were flying among the flowers. We know that some of our pollinators are in serious trouble, but my garden has nevertheless been blessed this year with a steady stream of pollinating visitors who were to be seen on the varied blooms morning, noon and almost night.
I’d enjoyed seeing the bees, butterflies and syrphid flies in the past, but started paying even more attention to them as pollinators this year as I worked on the “Healthy Bee, Healthy Me” project initiated by the non-profit organization Keep Durham Healthy.
The project expresses its goal as follows: “…to establish educational pollinator gardens in proximity to pre-existing community gardens to ensure the sustainability of nectar and pollen sources for our honey bees, native bees, butterflies and other pollinators throughout the year, and to increase the yield of the food crops grown within the community gardens.” Some of my photos were used in one of their interpretive garden signs and next year more community gardens will join the project.
Science knows that more than 250,000 plants are pollinated by over 100,000 different types of animals, but not all plants require assistance from pollinators for fertilization. In abiotic pollination, fertilization occurs without another organism as an intermediary – for example, through movement of pollen from male vegetative anthers to female stigma by the wind (called anemophily) or water (called hydrophily). However, much fertilization occurs with assistance from biotic vectors, which not only include bees, butterflies and flies but also moths, birds and mammals (e.g., lemurs, squirrels, opossums, monkeys and bats; here you see a hummingbird clearwing moth – Hemaris thysbe – getting nectar.) How cool is that!
The most efficient pollinators are the bees. Some species like honey bees (Apis mellifera) and bumble bees have pollen baskets (corbiculae) on their legs – a concave portion of their hind leg in which pollen can be stored as a ball. It starts out small but eventually gets fairly big so their little tibia begin to look like barbells. The color of the pollen can differ from bright yellow to brown to red to white, depending on the pollen of the flowers visited most often.
American bumble bee (Bombus pensylvanicus)
Common Eastern bumble bee (Bombus impatiens)
The attractive little honey bees, which vary in their coloring, are known to pollinate about one-third of the popular foods eaten by humans, including items such as tomatoes, peas, beans and other fruit.
When visiting tubular flowers, like the Brazilian sage (Salvia guaranitica), the bees don’t look for nectar by entering the flower as do the ruby-throated hummingbirds (Archilochus colubris) with their long bills. Rather, they alight on the base of the corolla tube so that they can drill down into the flower to extract the nectar at the source.
Honey bee Eastern carpenter bee (Xylocopa virginica)
The clearwing moths and butterflies, like the Eastern tiger swallowtails (Papilio glaucus), have long tongues that they use to probe the flowers as they hover. Nevertheless, they can get pollen on their legs or bodies and transport it to another plant, although they are not as efficient at this as, for example, the sweat bees and carpenter bees.
These bees have scopae rather than pollen baskets on their legs, i.e., structures comprising dense masses of compressed hairs into which pollen grains are pressed.
Small carpenter bee (Ceratina)
Female sweat bees (Augochlorella)
Long-horned bee (Melissodes)
Sometimes the bees manage to get their whole bodies covered with pollen, which can make species identification more difficult but creates some interesting views.
Wasps can carry pollen as I saw almost daily when the four-toothed mason wasps (Monobia quadridens) visited my yellow passionflowers (Passiflora lutea). Here you can see the pollen collecting on the head of a male, whose sex can be determined by the fact he has 7 abdominal segments and curved antennae (females have straight antennae and 6 abdominal segments). How’s that for a bit of obscure information for the non-entomologist?
The syrphid flies, often known as bee mimics, help pollinate, too. A number of these flies are honey-bee size and can be confused with the bees easily.
Flat-tailed leaf-cutter bee (Megachile mendica)
Transverse flower fly (Eristalis transversa)
Syrphid fly (Eristalis dimidiata)
Others are itsy bitsy, tiny flyers that can have pretty interesting abdominal patterns. I couldn’t see the patterns even with my glasses on; enlarging the photos revealed their beauty, which could make for interesting fabric patterns in my opinion.
Syrphid fly (Toxomerus marginatus) Syrphid fly (Toxomerus geminatus)
Syrphid fly with a lovely golden sheen (Eupeodes subgenus Metasyrphus)
The pollinators don’t appear to begrudge one another nectar – different species will share space on particularly popular plants.
Eastern carpenter bee and monarch butterfly (Danaus plexippus)
Eastern carpenter bee and sweat bee
Eastern carpenter bee, sweat bee and syrphid fly
Occasionally, the pollinators do not live out their usual short lifespans as predators catch them for food. This Chinese mantis (Tenodera sinensis) had been eyeing a bumble bee and was slowly moving toward it but the bee flew off before the mantis could complete its lunge. Later the mantis managed to snag a honey bee, however.
While on a walk one day, I suddenly was startled by the loudest buzzing I had ever heard, coming up behind me. It sounded angry, intense and was rather piercing for a buzz. I turned just in time to witness a giant robber fly (Promachus) settle on a grass stem with a bumble bee that it had just caught. The buzzing stopped fairly quickly as the fly proceeded to ingest its meal.
Various organizations and agencies, including the US Fish and Wildlife Service, are drawing attention to the endangerment of pollinator species. The main threats include loss and degradation of habitat as we pave over an increasing amount of natural space and plant lawns instead of native plants in yards. Using pesticides in landscaping areas is further threatening many of the insects on which pollination depends.
Planting pollinator gardens is a way in which we all can contribute to saving our pollinators; if you don’t have your own yard, you can volunteer with a project to create a community garden. And then you can watch these fascinating insects with appreciation for their contributions to us!