“Insects are those little things that run the world.” E.O. Wilson Insect numbers are declining world- wide at an alarming rate. A conservative view is that the insect population appears to be declining at a rate of about 9% per decade. Insects are a necessary and integral part of a healthy planet. They are of fundamental importance to all life forms and all terrestrial ecosystems. They are so important that insects total over 73% of all species on our planet! They provide many services including pollinating crops, trees, shrubs and flowers that many species including our own depend upon for food. They are responsible for passing on the sun’s energy, which they received from plants, to all other species in the food chain including us. Besides our native bees and honey bees, there are many other species including birds, other insects and bats, that provide the valuable service of pollination. In Blog #7, I wrote about hummingbirds and in Blog #13, I wrote about bats. Both of those species are pollinators. This blog is about native bees, their role as the primary pollinator of our planet and how to attract, support and sustain them in your garden and landscape environment. Evolution of bees: All bees are directly descended from wasps. Wasps are predatory insects, carnivores that eat other insects. When flowers started to evolve around 120 to 140 million years ago, some wasps discovered that pollen was a rich source of protein that could be collected and fed to their offspring without killing or being killed by another wasp. Gathering pollen for food and nectar for fuel for flight required certain adaptations different from those of hunters. Wasps’ bodies started to change shape to meet these new requirements and consequently morphed into the shape of bees. They became herbivores with hairy bodies all the better to trap and collect pollen. Some bee species like the bumblebee, developed sacks on their rear legs to collect and transport pollen. They developed tongues of different sizes depending on the species and the preference of the flowers they collect nectar from. Ones with longer tongues will prefer tubular shaped flowers like columbine or honeysuckle while bees with shorter tongues will prefer daisies, asters and sunflowers. Bees’ sense of sight is highly developed. They have two compound eyes, made up of many tiny lenses, and three simple lenses on the top of their heads. This evolutionary adaptation allows them a wide view of their environment so that they can find flowers through color and patterns. Flowers evolved with different colors and patterns to attract different size insects and species to pollinate them. Bees can’t see the color red which is a color more attractive to hummingbirds and butterflies. They are drawn to purple, blue, white and yellow. They also developed a great sense of smell. Perfume is the evolutionary adaptation of flowering plants to attract insects to pollinate them. Bees’ memories are highly evolved so that they remember where the best flowers for nectar and pollen are located. Native Bees are our planet’s most important group of pollinators. In North America there are over 5,000 species of native bees. There are over 20,000 world-wide. There are 356 native bee species in Massachusetts. Most people can only identify and are familiar with the bumblebee! Except for the colonizing bumblebee, named for the sound it makes while foraging, all native bees are solitary insects. They are usually seen only a few weeks a year when they emerge from their nests. Nests are found in the ground, in old tree trunks, in logs or in hollow stems of flowers and bushes. Upon emerging they immediately seek pollen and nectar, and in doing so pollinate crops and flowers. For the remainder of the year these bees remain hidden from view in their nests. The majority do not sting or make honey. Native bees range in size from 1/8 of an inch to slightly over an inch. They vary in color from dark brown, black, to metallic blues and greens. They also vary in shapes, life styles, places they visit, nests they build, flowers they visit and season of activity. One of the reasons they have evolved into so many different sizes and shapes is to match flowers that also come in different sizes and shapes. About 70% of bees, including the bumblebee, are generalists and collect pollen from a wide variety of species of flowering plants. About 30% are specialists and gather pollen from one specific plant species. An interesting note: Because native bees have evolved with all aspects of their environment including weather, in New England we see bees even in the winter months if the temperature is above 45 degrees. In general, most native New England insects can fly if the temperature is between 45-50 degrees. At that time they emerge from their shelters to search for any source of food that might be available, such as the winter blooming witch-hazel bush, (Hamamelis virginiana). The bumblebee is able to gather pollen and nectar from a wide range of flowering plants from March through November. Honey bees because they evolved in a warmer climate are only active when the temperature is reliably above 57 degrees. Honey Bees are not native to our country. They evolved around the Mediterranean Sea and hence are acclimated to warm areas. They survive here only if attended by beekeepers who provide a bee hive for shelter from our cold winters. Honey bees are raised by people who collect their honey. Humans have been collecting honey since Paleolithic times, roughly 2.5 million years ago. We know that Egyptians kept and tended hives. Honey bees were brought to this country in 1621 by the early colonists. They are social animals that live in colonies. They have a painful sting. In the United States honey bees are often raised in an industrial site and then transported by large trucks to areas that pay for their pollination skills. Most of our commercial crops use honey bees for pollination. A good example of this is the almond tree industry in California. It depends on trucks from honey bee farms in Texas to bring in bees to pollinate their trees when they bloom every spring. Basic Terms To Understand Pollination is the act of transferring pollen from one flower, tree or crop to another for the purpose of allowing fertilization. The evolutionary goal of every living organism on this planet, including plants, is to create offspring for the next generation. Fruit and seeds can be produced only when pollen is transferred between flowers of the same species. One of the ways that plants can produce offspring is by producing seeds. Pollination helps to maintain genetic diversity and resilience in the population of trees, plants and flowers, and helps develop adequate fruit, seeds or flowers. Plants need to produce enough seeds for both dispersal and propagation. Pollen is composed of protein lipids (fats). It is a fine powdery substance of microscopic grains, typically yellow, found on the male part of a flower, called a stamen, which produces the pollen. Each grain of pollen contains a male gamete, (sperm cell), that can fertilize the female ovule of the flower. Pollen is transported by insects, wind and other animals. Pollen transfer is essential for sexual reproduction of flowering plants, crops and coniferous trees that produce cones. Nectar is composed of carbohydrates and amino acids. It is a high source of energy and is used to for fueling flight as well as food. Services provided by native bees: Bees keep the world of native flowering plants going. Native flowering plants are the key component of most land ecosystems. Bees are found anywhere flowers bloom and are essential to their growth. Through pollination they transfer grains of pollen from the flower of one plant to the flower of another plant of the same species. Bees gather pollen and nectar for their survival. They make a pollen loaf out of pollen and nectar and feed it to their offspring. The Queen bee lays one egg on each pollen loaf. The emerging offspring’s survival depends on this food. Native bees are more efficient at pollination than honey bees. Only native bees use a technique called ‘buzz pollination’ when gathering nectar and pollen. The native bee uses its legs to grab the flower’s stamen, the organ of the flower that is comprised of the anther and a filament. It then vibrates its flight muscles thus releasing a burst of pollen from deep spores in the anthers. The anther is a key structure in the reproduction of flowering plants. It sits on top of the filament. It produces the male sex cells, stores them and provides a place to stay until the time comes when they are dispersed by bees. Worldwide state of bees: The decline of native bee populations in the United States and the world is increasing at an unprecedented rate. Today in the United States nearly 25% of the native bee species are imperiled and at an increasing risk of extinction. Some of the main reasons for this decline are: flowerless landscapes, destruction and fragmentation of habitat, loss of meadows and other areas bees once called home, competition with non-native bees, climate change, pollution, the planting of non-native flowers, plants and trees, and the use of insecticides, pesticides and herbicides. How to support bees: Create pollinator gardens – Like all species on this planet, bees need water, shelter, and nesting sites, (a safe site to raise offspring), as well as landscapes with native flowers and plants. When creating a pollinator garden, plant flowers with many different colors, patterns and shapes to attract bees of different species and sizes. Native plants are of utmost importance because they and the bees have co-evolved together. Plant native flowers, bushes and trees that bloom in different seasons from early spring to late fall so that bees have a constant source of nectar and pollen. Some good examples of plants are: Herbs - basil, rosemary, sage, thyme, borage, lavender, chives, dill, oregano, mint. Perennial flowers -sunflowers, anise hyssop, bee balm, heather, aster, columbine, lupine, baptisia, black-eyed susans, coneflowers, globe thistle, milkweed, coreopsis, daisies, phlox, gaillardia, yarrow, goldenrod, helianthus, zizia, black snakeroot, cosmos and Joe Pye weed. Annual flowers – alyssum, cleome, zinnias, salvia, calendula and verbena. Bushes – witch hazel, serviceberry, iron weed, aronia. buddleia, ceanothus, St. John’s Wort, buttonbush, rosa rugosa, elderberry, virginia rose, viburnums, sumac, winterberry and dogwoods. Trees – redbud, willows, red maples, wild cherry, horse chestnut, tupelo, basswood and black locust. Fruit bushes and trees – raspberry, blackberry, blueberries, cherry and plums. Stop using insecticides, pesticides and herbicides - they kill all insects including bees. Grow plants and vegetables organically. At the end of the growing season leave hollow flower stalks, garden debris and leaves in your garden throughout the winter. These places are where eggs, next year’s new generation, are finding shelter. Leave old standing dead trees and fallen logs. Both provide homes and shelter for bees. If you buy a bee hotel, it must be maintained and cleaned every year so that diseases and fungi will not be transmitted. Or you can buy new ones every year. Reduce your lawn area. Grass is a monoculture and does not support native insects. Add a new garden bed. Educate yourself about bees and pollinators. Here are some good books to read: “Pollinators of Native Plants” Heather Holm; “Attracting Native Pollinators” the Xerces Society; “100 Plants To Feed The Bees” the Xerces Society
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AuthorConsultant, designer and educator transforming commercial and residential landscapes sustainably Archives
March 2023
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