The most active time of year for bees are during the warmer months, from early spring to late summer. During this time, bees may invade buildings in order to establish new colonies and to seek shelter for when the colder months arrive.

A swarm of bees can be extremely aggressive and dangerous. When in a swarm, they are known to attack a human or animal in such large numbers that they are capable of killing. However, most bee stings are not lethal. They cause painful stings by injecting venom through a dart-like needle in their tails directly into the victim’s bloodstream. In some people this can cause swelling of the skin but in some cases people are so allergic to bees that their systems can go into shock, their airways shut down and they may die.

Different bees vary in shape and size. Their wings are membranous: the forewings are usually larger than the hind wings and have a coupling mechanism between the two sets of wings. They have chewing mouthparts, with some modifications for lapping or sucking. Their compound eyes are large in relation to the rest of the head. Females differ from males in that they often have an ovipositor, developed for sawing, piercing or stinging.