The red or two horned Osmia - Osmie rousse
This creature is for many an entomologist among the most celebrated of insects, for this genus of bees 'Osmia' was closely studied by the great French naturalist, Jean Henri Fabre. Fabre was born into a peasant family at St. Léons near Millau, and was in my view, the foremost entomologist of his day and father of behavioural studies in insects. A largely self taught man, late in life he received the Légion d'Honneur. His books still, a hundred years later, remain an inspiration.
The red Osmia is a common insect. The picture shows a male bee at the entrance to a drainage hole in a window frame. The previous year the entrance was blocked with mud by a female bee after creating cells inside, each with an egg. In spring the male bees emerge first from the cells just inside the entrance to the nest. The males are easy to recognise because they have large tufts of white hairs on their faces, as you see in the photo. These males dash around the entrance of the old nesting holes waiting for the females to emerge. They will bicker with each other for a prime position. The females are considerably larger than the males and have black faces with two small horns close to the eyes. In the instance of the window frame the holes used by the bees are no wider than a pencil. How is it that the males come out first and the females later? In all bees the males develop from unfertilised eggs and the females from fertilised eggs. Fabre showed that when the eggs are laid, the female can decide the sex of the offspring, by choosing whether or not to fertilise her eggs with stored sperm. She lays the eggs which will be female first in larger cells at the bottom of the hole, and then later the smaller male cells. Fabre discovered much of this by using hollow reeds and glass tubes as nesting holes. When a bee used several tubes, then always the female cells were formed first at the deepest part.
The cells are each separated by mud walls. They do not make cells of wax. As the bees mature, imprisoned in their cells, they turn about so that the head is directed towards the front opening - how do they know? Then they wait their turn to chew their way out. The wait is long. They have been in a chrysalis state since the previous August and it is almost a year since the egg was laid by their parent in a mass of pollen and nectar.