If you find a grounded bumblebee early in the year, just at the start of the first warmer days, then it is probably a queen. She may have been caught out in a sudden shower or a cold spell. If the temperature of the thorax falls below 30 oC the bumblebee cannot take off (see temperature regulation). The best thing you can do, after you have waited a while to make sure she is not just resting, is pick her up using a piece of paper or card, put her somewhere warmer, and feed her. When she has warmed and fed she will most likely fly off. You can feed her using a 50/50 mix of sugar and water in a pipette or eye dropper, or just a drop of this on a suitable surface within her reach, but be careful not to wet her hair or get her sticky. By saving a queen you may have saved an entire nest. If the weather is really unsuitable for letting her go, or if it is getting dark, you can keep her for a day or so if you are willing to feed her. I used to recommend using a honey/water mix, but there can be bacteria and all sort of stuff in commercial honey that I have stopped doing this.
A grounded bee found at the height or end of summer is another matter. Look at the wings. If they are ragged round the edges (see the photographs of wings) then you have either an old queen or an old worker. There is little you can do as really it is their time to die, however you could take them in and feed them if you wish, but let them go if they start to fly. If the wings are fairly intact then you have probably got a male that is either cold or has been so busy patrolling that he forgot to drink. As above you can take him somewhere warm and feed him, then let him go.
It is usually owners of medium to large dogs that ask this question. The dogs in question will often catch and eat flies too. In this case it is probably just the natural dog behaviour of catching something. If it is just bees the dog eats then it might be doing so for the sweet, nectar-containing honey stomach. I'm not sure if these dogs are immune to the sting or if they think the pain is worth the reward.
They are mating. It usually happens on the ground or on vegetation, but a strong queen can fly with a male stuck to her. For photographs see the life cycle page.
The noise cannot be caused by bumblebees as their jaws are just not strong enough to chew wood. However there are a number of other insects that can chew wood. In the U. K this noise is probably caused by social wasps as they need chewed wood to make their nest. In other parts of the world carpenter bees will tunnel into thick pieces of wood, and there are a number of beetles that chew wood and can make a noise loud enough to hear.
If you are finding a few dead or tired bumblebees in what seem to be closed rooms, usually bedrooms or bathrooms, then you probably have a nest in the attic. What can happen is that when an adult bumblebee is ready to go out foraging for the first time she will head to the nearest source of light. Now as this usually happens in the daytime that light comes from the outside. The bumblebee will form a mental map of the way from the nest to the opening, and all is well. However sometimes the strongest source of light is artificial, but he bumblebee still heads for it, this may be a hole in the ceiling, or a gap round a light fitting. The bumblebee crawls through the hole thinking she is outside, but she is trapped. The poor thing will bang herself repeatedly against any window in an attempt to get out, and usually die of exhaustion.
If this is happening in your house there is little you can do to help the bumblebees already in the room unless you can find the hole and put her back where she came from. Once you have done that you can block the hole with anything temporary, until you can make proper repairs. The material you use to block up the hole needn't be very strong as bumblebees don't chew. It just needs to be light tight. If you cannot locate the hole then you can try going up into your attic when it is dark, and getting someone to switch on the lights below. You should be able to see the source of light then and block it up.
This is probably a carpenter bee male, he is harmless as he has no sting and is looking for soon to emerge females.