Finding dead bumblebees in the garden...
Bumblebee nests grow throughout the season, and produce new males and queens in autumn. Throughout the life of the nest a large number of smaller worker bees help the nest to grow by collecting nectar and pollen - these are the bees that you see out and about in summer. These workers only live for a few weeks, and then sadly die. It's therefore quite normal to see a small number of dead bees in the garden. So long as you are still seeing live bees in the area, then it's unlikely to be something new that we should be worrying about.
The reason why dead bees are often found in gardens and near nest sites is simply because that’s where they’ve been living. When bees are close to death, they often cling to flowers and look quite lethargic. When they do die, they then drop off the flowers, and you may find a number of these in your gardens, especially near the most bee-friendly plants. Also, you may find dead bees and larvae near nest entrances, because dead and dying bees are removed from the nest so that disease does not spread.
Sometimes, large numbers of dead bumblebees can be found under lime trees. There has been a lot of research into the reason why and the current evidence points to the behaviour of bumblebees, and not toxic nectar. For some reason, bumblebees keep feeding upon the flowers, even when nectar runs low. So on hot days, and close to the end of the flowering period, the bumblebees keep feeding, run out of energy, and die. Honeybees, however, seem to realise that there is no nectar left, and will feed upon other flowers instead – smart honeybees!
Bumblebees, like many insects in fact (and humans!) can suffer from different parasites which live inside them. These parasites can make the bees appear slow and sluggish, perhaps even drunk! Again, sad as this may seem, it is a natural process that has been going on for many, many years and is not at the root of the problem.
Equally, bumblebees may sometimes seem very lethargic just because the weather is cold - but they will recover when it warms up. This is nothing to be alarmed about, and is perfectly natural.
“Bumblebees are one of the most endearing insect visitors to any garden. Their furry, colourful bodies and clumsy flight always raise a smile, but they also do an essential job. Without their pollination services many flowers would produce no seeds, and fruit and vegetable yields would suffer.”