Sunflower fields as critter-friendly habitats — part 2: bees and bugs

Do you know why the common name in English for Helianthus is sunflower? The common name is the same in Dutch (zonnebloem), German (Sonnenblume) and several other languages. In French (tournesol) and Spanish (girasol), the common names refer to “turning to the sun”, an accurate description of how this plant behaves.

Sunflowers exhibit a phenomenon known as heliotropism — an inclination to turn East in the morning so that the developing buds are warmed by the sun. The plant heads track the sun during the day and, at night, they reorient themselves to face East again. So if you pay attention when you visit a sunflower field at different times of day, you’ll notice they face a different direction in the morning and afternoon.

It’s not only birds, butterflies — and people! — that enjoy sunflowers. When these flowers grow in abundance, plenty of varied insects come to enjoy them and I’ll share something about these “sun worshippers” with you.

Bees of varying sizes were feeding in the sunflower fields that I visited. The large carpenter bees (Xylocopa) were not difficult to spot with their smooth shiny abdomens.

The similar-sized, fuzzy-looking bumble bees (Bombus) were actively visiting one sunflower after another.

American bumble bees (Bombus pensylvanicus) were foraging on nearby hibiscus blooms.

At a different site in neighboring Durham county, where sunflowers bloom later, I saw bumble bees on partridge peas and other yellow flowers.

 

There, too, my attention was caught by a bee that looked quite different from others that I’d seen. It proved to be a leafcutter bee (Megachilid), which has large mouthparts that enables it to cut pieces of leaves, plant resins and soil to line its nest.

The leafcutter bees are interesting in their unique method of carrying pollen. Rather than collect pollen in baskets called corbicula on their hind legs, they gather the substance in a clump of abdominal hairs called a scopa or pollen brush.

Back at the sunflower fields, I observed one medium-sized cuckoo bee (Epeolini) eventually become covered with sunflower pollen. These bees do not have an anatomical structure for carrying collected pollen and the females, like avian cuckoos (or cowbirds), lay their eggs in other bees’ nests.

The much smaller Western honey bees (Apis mellifera) were very numerous. It was interesting to discover that for some time, the NASA website included a section on honey bees! It stopped being updated when the principal investigator retired but NASA maintains the site because of the valued information it contains. Some of the interesting facts they listed about these insects:

  • Bees can fly about 20 mph (32 kph).
  • The highest recorded number of eggs laid by a queen was 2,000 per day!
  • Bees have been on our planet for about 30 million years!
  • To make 1 pound (0.45 kg) of honey, bees need to collect nectar from about 2 million flowers!!
  • The average foraging bee (all females) makes about 1/12th of a teaspoon of honey in her lifetime.
  • The main way in which honey bees communicate among themselves is via chemicals called pheromones.

The honey bees and common Eastern bumble bees make a good choice by spending lots of time in sunflower fields. Scientific studies indicate that ingested sunflower pollen enables them to suffer less infection from two common parasites, a real boon for bees who might otherwise succumb to colony collapse as a result of disease.

 

Both in the sunflower and other fields, it was fascinating to see other types of small bees as well. The small green sweat bees perhaps prefer more colorful blooms as that is where I mostly saw them.

These tiny non-aggressive bees are attracted to sweat because it provides them with moisture and salts.

There were some other interesting insects besides butterflies and bees in the sunflower fields and surrounding vegetation. While looking at some bumble bees circling a large sunflower head, I had inadvertently photographed a pair of much tinier insects near the center of the flower. I actually only noticed them when I was looking at the photos at home or I would have tried to focus on them better in the field.

When I enlarged the photo, I was able to get a somewhat fuzzy look at them and BugGuide identified them for me as sunflower seed maggots (Neotephritis finalis). These tiny insects have prettily patterned wings, but I discovered there is not a lot of information available about them; some research in North Dakota in 2008 concluded they might be a pest but no other data were easily available. They are a species of fruit fly.

Another insect seen on the sunflowers that many people find distasteful were the green June beetles (Cotinis nitida). The larva can damage vegetable and other plant roots, while the adults will feed on ripening fruit, so many gardeners will try to get rid of them.

A cute little syrphid fly, which BugGuide couldn’t identify specifically (a Palpada species), seemed to be alone with no fellow flies nearby.

There were several slender meadow katydids (Conocephalus fasciatus) to admire with their extremely long antennae.

The most interesting fact I discovered about them is that they have a soft song comprising ticks and buzzes that alternate for time periods of 1–20 seconds.

Sunflower fields are beautiful and spending time observing them as interesting wildlife habitats can really be enjoyable. These flowers also constitute a beneficial cash crop for farmers who can sell the seeds for sunflower oil, for human and avian consumption and the stalks for cattle feed.

And as if all those benefits don’t make sunflowers enough of a value-laden plant, scientific studies have also shown that they assist in phytoremediation, a process that helps remove and destroy polluting contaminants in soil, water, and air. Their deep taproots help aerate soil and make it richer for growing other subsequent crops as well.

Some sunflower fields may still be blooming through August and an online search can help you find them if you’d like to enjoy these wonderful flowers and their wildlife beneficiaries. If you have a garden, you might consider adding sunflowers to your vegetation mix if you don’t have them already. You can still plant some now in hopes of late autumn blooms.

This is a good time also to remember that the Ukraine became the world’s leading exporter of sunflower seeds until the currently ongoing invasion of the country brought this trade to a halt. Farmers who were still able to grow the country’s national flower are stuck with supplies and no income. Consider supporting organizations that are working to provide the Ukrainian people with humanitarian aid:

Busy as a bee is no joke! Our hardworking pollinators – pretty and persevering!

honey-bee-brazilian-sage-i77a1269-maria-de-bruyn-resHere 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.

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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.

 

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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.

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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!

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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.

 

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American bumble bee (Bombus pensylvanicus)

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Common Eastern bumble bee (Bombus impatiens)

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Honey bees

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.

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ruby-throated-hummingbird-i77a1315-maria-de-bruyn-resWhen 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.

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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.

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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.

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Small carpenter bee (Ceratina)

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Female sweat bees (Augochlorella)

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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.

eastern-carpenter-bee-i77a2601-maria-de-bruyn-res    eastern-carpenter-bee-i77a3750maria-de-bruyn-res

four-toothed-mason-wasp-monobia-quadridens-i77a2039-maria-de-bruyn-bgWasps 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.

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Flat-tailed leaf-cutter bee (Megachile mendica)

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Transverse flower fly (Eristalis transversa)

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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-i77a5952-maria-de-bruyn-res   syrphid-fly-toxomerus-geminatus-i77a5943-maria-de-bruyn-res

Syrphid fly (Toxomerus marginatus)                      Syrphid fly (Toxomerus geminatus)

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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.

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Eastern carpenter bee and monarch butterfly (Danaus plexippus)

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Eastern carpenter bee and sweat bee

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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.

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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.

 

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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.

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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!