Hello Mid-Ohio Valley Farmers and Gardeners! Thank goodness for the recent rains we have received. Many areas in the Valley are still very dry. Many livestock farmers are feeding hay but pastures will recover if we continue to receive rain. Many residents have told me they did not mow their lawn for four weeks straight. Lawns that were mowed at a higher deck height are recovering much faster. Folks, this is why I recommend a 3-inch or higher cutting height.

Many gardens look good thanks to diligent watering by backyard gardeners. If you have transplants available, now is the time to start the fall garden with broccoli, cauliflower or Brussels sprouts. You can plant leafy greens such as lettuce, spinach, Swiss chard and kale.

This week I want to talk about bumble bees (genus Bombus in the order Hymenoptera). Yes, these very large bees are intimidating due to their size and loud buzzing, but they are important pollinators of food crops and many plants in our landscape.

Many people are afraid of bumble bees. Yes, they will sting to defend themselves and their nest similar to most other stinging wasps and bees. Bumble bees, are much less likely to sting than hornets, yellow jackets or honeybees. Be careful, unlike honey bees, they are able to sting multiple times.

Bumble bees forage and pollinate many wildflowers and native plants and are pollinators of economically important crops that benefit from buzz pollination including tomatoes, eggplants, cucumbers, potatoes, cranberries, blueberries, squash, alfalfa, and clover.

Several species of bees, including bumble bees, use a special strategy called “buzz pollination” to pollinate flowers, especially on plants such as tomato flowers. It is an especially effective means of dislodging pollen from plant anthers via wing vibration. Bumble bees engage in this pollination behavior, which requires them to grasp the anthers of a flower and vibrate rigorously to dislodge the pollen.

How does it work? Buzz pollination occurs when the bee vibrates its thoracic muscles at a very high frequency. This causes the pollen to bounce off the anther of the flower and land on the fur of the bumble bee. When the bee travels to new flowers, this pollen is transferred between flowers, completing pollination.

Tomatoes do not produce nectar, so their only reward to draw in pollinators is pollen. This greatly influences the type of bee best suited for use in tomato greenhouses. Honey bees do not perform buzz pollination, and when given access to other floral resources they will not readily choose to pollinate tomatoes.

Another cool thing about bumble bees is they are very good at pollinating blueberries. Research conducted at the University of Maine indicates that commercially available bumble bees (Bombus impatiens), are excellent pollinators of wild blueberries.

This commercial bumble bee handles flowers faster than honey bees or alfalfa leafcutting bees and is more faithful to the blooming crop, even if alternate forage is in flower at the same time. They also possess the ability to fly at cooler temperatures than honey bees and will visit blueberry flowers even in moderate rain.

Bumble bees do not require additional shelters, incubation equipment or nest materials. Commercial bumble bees arrive from the supplier ready to be placed in the field. However, they may be more expensive to use than honey bees because they must be purchased and cannot be used again.

Many people love tomatoes, and bumble bees are excellent pollinators for greenhouse and high tunnel tomato growers. Bees vibrate the flower as they collect pollen for feeding. Bees are active from sunrise to sunset and at low temperatures (as low as 41°F), and in windy and cloudy conditions. Excellent pollination results in larger and heavier fruits.

In the United States there are approximately 49 known species of bumblebees. There are over 260 species of bumblebees identified across the globe. Most species are encountered in the Northern Hemisphere, but there are species located in Central and South America and northern Africa.

Here in West Virginia, data collected in 2016 by Aliff and Collins in Kanawha County indicated the bumble bee community is dominated (95% of total specimens collected) by three species including the Common Eastern (B. impatiens), the Two Spotted (B. bimaculatus) and the Brown Belted bumble bee (B. griseocollis). This pattern of diversity is similar to collections found in other regions of North America.

Bumblebees generally are large bees with black and yellow hairs all over their bodies. They can be distinguished from other bee species by the pollen basket (corbicula) on the female’s hind legs, which is usually flattened, concave, and with hairs only around the outer edges. Honeybees also have pollen baskets.

Bumble bees are 1/4 to 1 inch long. The bumble bee queens are typically twice as large as workers or males. A female bumble bee has a pointed abdomen with a stinger. Males do not have a stinger and the tip of the abdomen is rounded.

Although they both are social insects, there are some differences between bumblebees and honey bees. Bumble bees are an annual species which have one queen per year, whereas honeybees are perennial with one queen that can live for up to five years. The annual bumble bee’s life cycle is a fascinating process where the queen transitions from a seasonal solitary phase and progresses to a social phase later in the cycle.

The bumble bee colony is made up of three types of individuals including queens, sexually undeveloped female workers, and males. Bumble bees produce annual colonies but only the mated queens overwinter. Nests are started in early spring by these solitary, fertilized queens. These queens are often seen feeding on spring flowers or searching for a suitable nest site.

In the spring, each new bumble bee queen selects a nest site and starts a new colony. Normally, nests are established in an abandoned rodent or bird nest in the ground. She lines the cavity with dry grass or moss and then collects pollen and nectar to produce a stored food called “bee bread.”

Similar to honey bees, bumble bees work together as a colony through the late spring, summer, and fall months. The queen is the only one in the colony to lay eggs, while the workers maintain the hive and bring in local pollen and nectar resources.

Male drones have fewer responsibilities to the colony and are less abundant than the workers. Their purpose is to mate with virgin queens that are typically reared by the colony during late summer. Task allocation is also a feature shared by both honey bees and bumble bees.

Bumble bee division of labor is correlated with body size, where larger bees can carry more pollen, and smaller bees perform in-colony tasks, such as caring for brood. In honey bees, the division of labor is dependent on age. Younger workers feed and care for the developing brood, while older workers are foragers. As new workers emerge, the more senior workers will adopt new colony tasks according to age.

Nectar is collected and stored in small sac like “honey pots” built from wax and pollen. The workers enlarge the nest and by midsummer the colony will have 20-100 workers.

The queen continues to lay eggs throughout the summer. By late summer, new reproductive males and females (kings and queens) are produced. They leave the nest to take mating flights.

Successfully mated queens fly to the ground and hibernate 2-5 inches deep in the soil or move to hibernation sites in the shelter of loose bark, hollow trees or other dry, protected places to lie dormant through the winter. The males and workers still in the colony die with frost or the first hard freeze. The overwintering queens emerge the next spring to complete the life cycle.

Bumble bee populations are in decline and should be protected and encouraged. They face numerous challenges such as increased pesticide use, habitat loss or fragmentation, climate change, diseases, and natural enemies. To reduce habitat fragmentation, land should be managed carefully to minimize effects on bumblebee colonies. Backyard gardeners, consider developing more nesting habitats, such as planting tall grass strips and providing wildflower landscapes to promote bumble bee colony survival and success.

Contact me at the Wood County WVU Extension Office 304-424-1960 or e-mail me at jj.barrett@mail.wvu.edu with questions. Until next time, Good Luck and Happy Gardening!