Thursday, April 17, 2008

Bumble Bees

I had some email replies to yesterdays article asking what people can do to promote pollination for their gardens and for the environment since there are few wild honey bees found locally any more.

There is actually a great deal individuals can do. Today and tomorrow I will post articles on native pollinators. I hope this info helps.

SCIENTIFIC CLASSIFICATION: Bumble bees belong to the genus Bombus of the family Apidae, order Hymenoptera.

SIZE: 3/4 to 1 1/2 inches (19.1-38mm)

COLOR: Generally black and yellow

DESCRIPTION: Bumble bees are large, hairy bees that collect and carry pollen on their hind legs to bring it back to the hive. Bumble bees are beneficial insects.

HABITAT: Primarily found in temperate regions of the northern hemisphere, often ranging farther north and higher in altitude than other bees. Fifty species of bumble bees are known in North America. They are most often encountered while foraging at flowers. They may nest in wooden storage sheds and small barns, in trees with natural cavities, and in cavities in the ground.

LIFE CYCLE: A queen, who is the egg-layer, heads Colonies. Workers are the daughters of the queen. Drones (males) are produced during the mating season in mid summer. Unlike the honeybee, the bumble bee colony only lives for one season. The new queens mate with drones in late summer and then hibernate alone through the winter. All drones and workers die before the winter. The new queen will emerge in spring to start a new colony. They normally do not reuse the hive from the previous year.

COMPARISON TO HONEYBEES: Strong bumble bee colonies may only have a population of 200 bees as opposed to the honey bee colony which may have several tens of thousand in their population. The bumble bee worker can use its stinger more than once and live to sting again, unlike the honey bee who can only sting once and then dies leaving its stinger behind. They do not use dance to communicate like the honeybee. Bumble bee and honeybee drones have no stinger. Bumble bees do not hoard and store honey like the honeybee, they use it as feed for their young and for the hive. Since only the queen survives the winter there is no need for honey stores to hold a colony over.

COLONY: The bumble-bee nest consists of a spherical chamber with a single exit. The queen chooses a preexisting cavity, such as an abandoned mouse nest, in which to begin her family. Most species nest in the ground. The queen forms a small mound of pollen paste in the middle of the nest, lays several eggs in it, and seals it with a small dome of wax. She also constructs a hemispherical wax cup, called a honey pot, in the entranceway floor and fills it with nectar. The queen feeds on this nectar while she incubates the eggs. The newly hatched larvae partially consume the paste in their cells. They are later fed by the queen through a small opening in the cell wall. When the larvae are fully grown, they spin cocoons in which they metamorphose, eventually emerging as the first workers of the new colony. The workers rear subsequent larvae in individual cells. Workers are small if born early in the year, and large if born later in the year.

POLLINATION: Bumble bees are important pollinators of many plants and are able to work in colder temperatures than honeybees. Both queens and workers collect pollen and transport it back to the colony in pollen baskets on their hind legs.

NEST BOXES: A bumble bee nest box is easy to build. You can attempt to lure a new queen into taking up residence by your garden. It is best to have more than one box. This does not guarantee that bumble bees will move into the boxes you provide every year, but the chances are good if you place boxes near areas where you have seen them foraging.

The boxes should be placed in full or partial shade. The entrance hole should be from 4" to 10" off the ground in an area where there is no possibility of flooding the entrance. The nest box needs to be elevated to prevent excessive moisture. Place weights on the cover to insure that weather and animals cannot remove it. Place it where children, pets or lawn mowers will not disturb it.

If no colony has been established by the end of July, return the nest box to storage until next season. Your nest boxes will last a long time since they will only be exposed to the weather during April, May, June, and July each year until they get a colony. Bumblebees emerging from hibernation in early spring are fertilized queens. They may search for up to two weeks to find an "ideal" nest site. A spring queen with pollen in her pollen baskets has already found her nest site. Avoid checking the nest box for activity. If a queen is disturbed before really settling-in, she will most likely move on. If you get one box in three occupied, you have been fortunate. Reinstall your nest boxes every year, and hope for the best.

A bumble bee nest is rectangular box which measures 6 inches tall, 6 inches wide and 13 inches long. Inside it has two compartments. The first measures 5 inches by 6 inches and serves as a staging ground where bees will defecate and set up defenses from the main nesting cavity located at the back of the house. The back or main cavity measures 8 inches by 6 inches and this is where queens will spend their lives.
Place cardboard on the floor of both chambers. This will make annual cleanup easier. Place cotton or wood shavings in the larger chamber to act as a nest.

You may also build in a covered peep-hole on side with sliding wood cover and protective screen. This allows visual inspection of the main nest chamber so you can view bees once they are living inside. It can also serve as a vent by keeping just slightly open if house is kept in excessively hot region.

WHERE TO USE IT: Outside where bumble bees are active. This could be in a garden, along a fence row, under hedges, between elevation breaks, by a flower bed, around mulch piles and just about anywhere bumble bees have been seen foraging. There really is no limitation or restrictions and since they make a great conversation piece, the more the merrier.

Construction and Placement of Bumblebee Nest Box

Scrap plywood (1/2 inch to 3/4 inch thickness.)
A rough cut 2 x 4 (such as cedar) about 6½ inches long.
3/4 inch pvc pipe, 6 to 8 inches long.
1/8" x 8" x 15" clear acrylic panel (optional, but practical)
Front and back each 5½" high x 15" wide
Sides each 5½" high x (8" minus two times the thickness of the material used), e.g. if using 3/4" plywood, the sides pieces will be 6½" wide.
Bottom 10" x 15"
Top about 14" x 17"
Acrylic panel 8" x 15"

Drill vent holes near the top of the side panels. Cover with fine screening which should be glued or stapled firmly into place. Assemble side panels to front and back panels to form a box as in the diagram. Fasten the box to the bottom plate with the landing area extending to the front as shown. The diagram shows that a 3/4" hole should be drilled through the 2 x 4 connecting the two chambers about an inch from the back of the box. Fit the roughly surfaced 2 x 4 to the bottom plate, front panel, and back panel, so that two chambers are formed. One chamber should be 5½" wide and will serve as a vestibule. The brood chamber will be 8" wide. There should be 2" of air space above the 2 x 4. Surfaces of the 2 x 4 need to be rough so that the bumblebees can climb over it with ease.

Drill a hole in the front panel to accommodate the pvc pipe. The pipe should extend from the front panel up to the hole in the 2 x 4. Before installing the pvc pipe, spray the interior of the pipe with black paint. Spring queens will be looking for mouse holes, so you want to minimize reflected light inside the entrance pipe. The pipe should be held in place by a tight fit in the front panel and by some glue or caulk between it and the bottom plate. Place a small quantity of upholsterer's cotton in the brood chamber.

The acrylic panel need not be installed unless you wish to inspect an established colony. Certain species such as B. fervidus and B. pennsylvanicus are known to prevent such inspections. Most others range from "slightly more forgiving" all the way to "quite docile." I prefer to install the panel so that an energetic skunk or raccoon that is large enough to remove the top cover will still have no access to my bumblebees.

The top cover should have some type of drip cap installed all around the perimeter of the underside so that no water could run toward the box. This could be done with 1/4" to 3/8" quarter round molding or any wood or metal scrap. The exterior portions of the box should be sealed and painted because there is no way of knowing how many years before any particular box gets a colony. There is no need to finish the interior of the box, because it is protected from the weather and should you be fortunate to attract a colony, it will be necessary to discard the box at the end of the season of actual use. Discarding a used nest box is important because there is no practical way to sterilize a wood box. There are a wide variety of parasites, which feed off bumblebees and the nest contents during the season. Eggs of these parasites may be deposited in cracks and crevices. Nest boxes constructed of metal or plastic could probably be cleaned with steam or chemicals. Wood boxes are quickly made, and easy to replace.



Blogger Beth said...

There is no way in hell I could build one of those - perhaps I can buy one?
I am so impressed with this post.

6:01 AM  
Anonymous Anonymous said...

You answered many of the questions on the back burner of my mind concerning these fascinating physic defying creatures. Years ago I was painting a house in Astoria while working on the south facing peak there was a steady stream of bumbles entering and exiting a knot hole that would have led to a space between the siding and the interior wall. I wondered how long the nest had been used, how much of what kind of honey might be inside and whether I should tell the home owners that they might have a problem. Now I know and am glad I didn't narc them out.

6:46 AM  
Anonymous Anonymous said...

I guess I,m glad I didn't narc them out. Do you think those parasites present a danger to humans or just bumblebees? It's been years and every one is in good health.

6:54 AM  
Blogger Syd said...

I assume this would be an inappropriate time to ask how to the kill the fuckers that are boring into my house...

7:47 AM  
Blogger The Guy Who Writes This said...

Beth, you don't need a box, they will find their own homes. Hint, they love discarded mattresses. You may be able to find a bumble bee box in a nature shop or a feed store. It is really hard to attract them. It's really hit or miss. There is something to buy in tomorrows post. Stand by...

Anon, they don't reuse their nests or reclaim old nests. Their parasites are not harmful to people and there are enough to go around to work future generations. They only produce enough honey for their daily needs, not like honey bees that produce much more than they could ever eat. When the bumble bees die off and leave the nest vacant, honey bees may occupy it, so it is a good idea to seal the hole when the winter comes around.

Syd, that's what you get when you live in a log cabin. You made a home out of their home. You're lucky you don't have beavers in Mississippi...well, you know what I mean...

8:53 AM  
Blogger The Guy Who Writes This said...

BTW they probably using holes that something else is boring. Treat your wood.

8:57 AM  
Anonymous Anonymous said...

I had a bumblebee colony last year in a birdhouse that had been used the year before by a chickadee family. Also, several years ago I bought a regular bumblebee house for my daughter from a garden supply catalog.

9:08 AM  
Anonymous Anonymous said...

Glad to hear the parasites aren't harmful. I'll see if honey bees followed up on that hole near the peak. That home is hidden in a really sweet spot on Astorias south slope. Lots of great habitat around it, a medium yard with flowers around the edges and beyond, a nice assortment of wild stuff like fox glove, fire weed, salal, scotch broom probably some berries and a nice mix of hard woods and conifers.

9:52 AM  

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