are the dangerous

This is a photo of a black bee - a Carpenter bee.  If this is what you
are asking about then the following will be helpful to you.

http://www.bug-guy.com/junepest.jpg

Carpenter bees are another common example of a solitary bee. The
hairy, bluish?black bees you see visiting flowers or hear buzzing by
each spring are female carpenter bees. They are over one inch long and
about as wide as your thumb. Female carpenter bees are capable of
stinging, but are not normally aggressive. They do not sting unless
trapped, stepped on or otherwise endangered.
http://ag.arizona.edu/urbanipm/insects/bees/solitarybees.html

if its a black honeybee beware of swarming.THey are the africanized honeybee.
If its The big black bumblebee (carpenter bee)very harmless.some
may/can sting but the ones with the white dot in its face either can't
or won't sting.