Leafcutter bees

I am always impressed at how obliging wildlife can be when we try to attract it to our gardens: put up a bird box and before long it will be occupied by a blue tit, dig a hole and put some water in it and as if by magic a whole wealth of aquatic creatures will appear. This year we put up a solitary bee home, and lo and behold, solitary bees appeared. It was fascinating to watch them as they went about their business, and highly impressive to see the rate at which they made the tube-filled log their own.

Most people imagine bees to be highly social creatures, living in large colonies to do the bidding of an all-powerful queen. This is indeed the case for common bumblebees and honey bees, but there also exist a number of solitary bee species, of which the leafcutter bee is one example. Leafcutters are fairly small bees at about 10 mm long. Their bodies are a dark brown with a dip in the abdomen where they store pollen; this differs from other bees which store pollen in sacks on their legs. They don't live long, normally only for two months, but they fill this brief existence with frantic activity

Upon emerging from its nest the female bee quickly finds a male with which to mate. Once it has done this it goes about finding a suitable nest site, ideally somewhere providing a hollow tunnel of a similar width to the bee itself, although it can dig out a tube if necessary. The nest could be in the stem of plants such as roses, in the soft depths of decaying wood, or in the tubes of a shop-bought bee home. Once a site has been located the bee will start collecting leaves. Whole leaves would be rather awkward for the little bee to carry, and so instead it cuts out small semi-circles which it carries back to the nest. It then uses these to fashion several compartments in the previously-constructed tunnel, into each of which it leaves an egg and a ball of pollen and nectar before sealing it up. Once the nest is completed the bee abandons it to fate.

Each female leafcutter bee lays up to 40 eggs, which means up to 40 compartments need to be made - this equates to an awful lot of leaf building material and explains why the bees are so busy. Life for the larva is rather more sedate. It soon hatches and consumes the ball of pollen left for it, then hibernates for the winter. The following spring it comes round and pupates, emerging as a fully-fledged bee at the beginning of summer. Males tend to develop in the compartments closest to the end of the nest, and so emerge first. Their sole purpose is to mate with the females, and after they have done so they die, taking no part in the nest-building process.