Why are bees inside my house?
Consequently, what attracts bees to my house?
Unused appliances or lawn equipment found in yards can attract honey bees since they provide sufficient shelter for a hive to thrive. Also, if your home has previously had problems with honey bees, make sure the honeycomb is removed. The pheromone scents left on honeycomb can attract newcomers.
Subsequently, one may also ask, why do bees die inside the house?
Bees are swarming this time of year as colonies split up and a queen flies off with part of the hive looking for a new home. The lethargy, and death, may have been caused by the bees getting too cold or running out of food. That they chose your windowsill indicates there is a hive close by.
If you find a lone bee on the ground or in your house that looks exhausted try moving it somewhere safe outside and giving it a solution of sugar and water. This may well save it and provide it with enough energy to return to its nest. Do NOT give it honey as this can contain traces of viruses from wild bees!