Bumblebees

Biology

Bumblebees are colonial, annual insects. The queen will overwinter until early spring. Under normal circumstances, the queens would emerge over a period of a couple weeks. After she emerges, she will enter new soil and build small honey pots and brood cells. The first bees to develop with the warmer weather are the small workers. They will then take over the queen's duties (except egg-laying) and construct larger brood cells and honey pots. This in turn creates larger adult bees. They fly from May to September. Adults can reach up to ¾-inch.
Adults drink nectar and eat honey. Larvae tend to only feed on honey.
At the end of the season, only the young mated females overwinter. The rest of the colony dies, including the old queen. Colonies can house between 50-400 bees.
Most Bumblebees nest in the ground, usually in deserted bird or mouse nests. However, they have also been known to nest in the cracks of woodpiles, in discarded padded furniture or piles of clothing in garages or sheds.
Unlike a honeybee, bumblebees can sting many times. However, they are also quite non-aggressive and will only sting if they feel it is necessary. Remain calm around them and you will not get stung.
Vibration is the stimulus that renders them the most aggressive.

In general, bumblebees are beneficial garden insects, being important for plant pollination. Avoid killing them unless absolutely necessary.
Ammonia is a good repellent, but exclusion is the only permanent solution.

Important Note: Only approach the nest on a cool evening, at night or at dusk. Wear protective clothing, gloves, a hat and a face net.