All summer I have been keeping a keen eye out for bees of any kind, but especially the bumble bees because in the last few years after the honey bee collapse these fuzzy insects seem to have increased their numbers helping to pollinate flowers, vegetables, trees, and shrubs around my house.
Until lately, I have been very disappointed because relatively few bees have been around my very wild flower gardens. I have seen exactly two honey – bees all summer. Some mud and miner bees have been present but I have fretted about the bumble bee absence.
A week ago when my beautiful white hydrangea bush, now as big and bushy as a tree (not the popular variety known as PG) finally began blooming I glimpsed Bombus ternarius commonly known as the orange belted bumble bee visiting the clusters of pure white blossoms along with a number of other native bees. For the first time all summer there were enough bees pollinating the flowers to create that lovely bee hum that I used to take for granted. I was so delighted I recorded a video as much for the sound as for the sight. I find myself repeatedly returning to my pearl white bush (that positively glows in the light of the full moon) to hear a bee symphony.
Unfortunately, some North American Bumble bee species are experiencing significant population declines. Several species including four native to Maine were once very common and now are rarely observed. The usual culprits, habitat loss and fragmentation, pesticides, herbicides, and diseases and parasites introduced through widespread use of commercially raised Bumble bees are part of the problem, but so little research has been done overall that it is difficult to assess the status of the sixteen or seventeen species (statistics vary according to the source consulted) that are known to live in Maine according to the Maine Bumble Bee Association.
Bumble bees are social bees and belong to the same family (Apidae) as honey bees because the females store collected pollen in special pollen baskets on their hind legs. The queen is the largest bee (and she alone will winter over), workers, also females, do not lay eggs, and the males (drones) are most active during the late summer and fall. In Maine, Bumble bee colonies rarely exceed more than 40 individuals.
Bumble bees visit flowers even in cold rainy weather and are superior pollinators. Some species live below ground, others above ground, and a few appear to have no preference. Nests appear in abandoned rodent habitats, in undisturbed meadows and pastures, abandoned bird nests, cavities in rock walls, foundations, and other sheltered areas.
Bumble bees are robust in appearance but their color patterns are often highly variable within species. Curiously they are often similar among groups that inhabit the same geographic region. I wonder if the buttery yellow Bumble bees that love my scarlet runner beans and nasturtiums are the same species as the orange belted bumblebees that loves my bush. They are exactly the same size, small by Bumblebee standards, but otherwise appear identical.
Bumble bees can be found all over the world in Asia, Europe, North America, Central and South America. They are typically found in higher latitudes though exceptions exist. I know from experience that lowland tropical species of this bee exist (Peru). A few species even range into very cold climates like the arctic where other bees might not be found. One reason for this is that Bumble bees can regulate their body temperature, via solar radiation, the internal mechanism of “shivering,” and by radiative cooling from the bee’s abdomen. Other bees have similar physiology but this phenomenon has been well studied in Bumble bees.
Bumble bees extract nectar from a flower using their long tongue and store it in their crop. Some species also exhibit what is known as “nectar robbing.” Instead of inserting their tongue these bees bite directly through the base of the corolla to extract nectar. These bees obtain pollen from other species of flowers that they visit.
Pollen is removed from flowers either deliberately or accidently. Incidental removal occurs when Bumble bees come in contact with the anthers of a flower while collecting nectar. The body hair of the bumblebee receives a dusting of pollen, which is deposited in the pollen baskets.
Once collected, Bumble bees return to the nest and deposit the harvested nectar and pollen into brood cells (made of wax) for storage. Because Bumble bees only store a few days’ worth of food they are much more vulnerable to food shortages. However, because they are much more opportunistic feeders than honeybees these shortages may have less profound effects. Nectar is stored in the form it was collected rather than being processed into honey.
Bumblebees form colonies but they are small with the female being responsible for the construction of the nest, and that nest only lasts for one season (except for some tropical species). The last generation of summer bees includes a number of queens who overwinter separately in protected spots. The queens live at least one year; the workers die at the end of the season.
Bumble bees have a unique genetic system whereby mated females control the sex of their eggs, with daughters developing from fertilized eggs and sons from unfertilized eggs. Unmated females produce only sons.
In temperate zones during the autumn young queens mate with drones and sleep during the winter in a sheltered place.. Early in the spring the queen emerges to find a suitable place to create her new colony. Then she builds wax cells in which to lay her fertilized eggs. The eggs that hatch develop into female workers and in time the queen populates the colony, with workers feeding the young.
Bumble bees are being raised for agricultural use because they can plant species that other pollinators cannot by using a technique called buzz pollination. For example, bumble bee colonies are used in greenhouse tomato production because the frequency of buzzing effectively releases tomato pollen. This is a perfect example of species interdependence – something we know almost NOTHING about.
In these times of uncertainty and climate change it is even more important to take whatever conservation methods we can utilize to maintain our Bumble bee populations. What follows are some tips to help conserve these bees (and others).
- Minimize lawn areas – mow less often – mowing kills bees – mow in the evening or on windy days when it’s cool and overcast.
- Keep gardens and grow fruit bearing trees and shrubs – provide a succession of flowering periods beginning in the spring and lasting into the late fall
- Plant wildflowers in the spring for those early pollinators
- Avoid marigolds and other hybridized plants that have no pollen (they are sold for blooms only)
- Tolerate dandelions and other “weeds” like mullen, wild primrose, queen anne’s lace, st john’s wort, wild violets, milkweed and goldenrod.
- In the fall let your ground fruit rot
- Provide an area of undisturbed ground/dirt somewhere on your property
- Create brush piles
- GIVE UP ALL PESTICIDES AND HERBICIDES.
Give our pollinating friends a chance to help our plants grow. Remember that without bee pollination we would have no food to eat.