What's bugging you? Oct. 18, 2017

By Jim Leser


What's bugging you? Oct. 18, 2017 | What's Bugging You, Jim Leser,

Hunt's bumblebee on lavender

Another bee beastie that can be observed in our gardens are members of the genus, Bombus, or bumblebees. I like to refer to these as the teddy bears of the insect world as they are plump and furry.

There are over 250 bumblebee species in the world, found mostly in temperate or semitropical zones. They prefer cooler areas and hence will be most numerous at higher elevations or latitudes. We have about 50 species in North America with 12 found in Colorado. Most have contrasting bands of black, buff, yellow or orange colors on their abdomens.

My favorite bumblebee is Hunt's bumblebee, Bombus huntii. This species is quite attractive with orange on its abdomen (see picture). But what seals the deal is that this bumblebee was the object of my research during my master of science degree studies. I was looking at temperature regulation in bumblebees in relation to foraging strategy. My bumblebee was found at 8,000 feet in the Spring Mountain range in southern Nevada. But it is also found right here in Cedaredge.

What most people do not know is that bumblebees can regulate their body temperature by shivering, rapidly contracting their thoracic muscles. In fact, they can't fly until their temperature reaches at least 86 degrees Fahrenheit. And they can fly at temperatures below freezing as long as they warm up before leaving their nest. They use heat dissipation from their abdomen, much like a radiator, to keep their temperature below 110°F during hot weather.

Bumblebees are social insects and generally nest below ground. They do not build an organized nest or hive like honeybees. Their numbers are much lower too, ranging from 50 to several hundred. Honeybee hives average 50,000 or more bees. Worker bumblebees range in size from 1⁄4 to 1 inch. Of course queens are larger. Queens produce the wax used in building their nest structure.

New queens and drones (males) are produced in the fall with fertilized queens overwintering in the ground elsewhere. Otherwise, all bumblebees you will see are workers and hence female. Surviving queens emerge from hibernation in the spring to start new nests. The old queen does not survive the winter.

Unlike honeybees, bumblebees can sting multiple times as their stingers do not have barbs on their ends. But bumblebees as a whole are quite docile and go out of their way to avoid confrontation. They do make honey but store very little of it in their nest. And their honey is not edible by humans.

Bumblebees are good pollinators and are an asset to agriculture. Their long tongues allow them to feed on nectar in tubular flowers. Honeybees cannot. Early in the year they will feed on fruit tree blossoms and then flowers of geraniums, honeysuckle, salvia, catmint, roses, wisteria and other suitable plant flowers. Later in the summer, sunflowers, lavender, hollyhocks, cosmos, snapdragons, followed by flowers of cucurbits and many other vegetables are utilized.

Bumblebees collect both nectar and pollen. Right now bumblebees are visiting rabbitbrush and blanket flowers in my yard for pollen, right along with numerous honeybees. Isn't it great to have a garden that attracts such interesting visitors? You too can increase the interest in your garden if only you plant the right flowers.

Jim Leser retired to Cedaredge in 2007 after a career with Texas A&M University Extension in entomology. He is a member of the Cedaredge Tree Board and a Colorado Master Gardener.