Solitary Osmia bees (O.rufa and O.cornuta) are native in Ukraine and they are widespread species. These bees build their nests in natural tubes and different cracks in stones, in wood, or between bricks. As there are many favourable places for their nests where people live, there is a good urban population of these bees. 
These species abound during the springtime their active period of life coinciding with the blossoming of garden fruit trees. Because of this they are useful pollinators in gardens and have two advantages in comparison with honeybees: they are able to work at a lower temperature and the effectiveness of pollination, at one visit, is essentially better. Osmia rufa is the more northern species and is found even in Northern Europe. Osmia cornuta’s northerly limit of distribution almost coincides with the northern border of Ukraine. From my own point of view the O. cornuta bees are the most beautiful bees in the world, they are like small black and red bumble bees. In some localities the density of population of osmia bees is very (or even extremely) large. 
As a rule, in such places the nest cavities are in abundance. However, conversely. there are localities where these bees are completely absent and this fact hasn’t a simple scientific explanation. 
Similarly, there seems to be no reason why in some areas there are very significant changes in the density of population of these bees. Many examples are known of villagers having constant problems with keyholes being sealed with clay by the osmia bees. Once my friend had the problem of having to clean the rubber oil hose in his car as it was choked up with osmia bee nests. In one village, where there were many old sheds with the reed stem roofs, I observed the flight of many insects like bees from a hole in the vertical clay wall. The intensity of their flight was similar to that of a very strong honeybee colony. At first I thought that it was a very rare and interesting case of a honeybee swarm living in an underground nest. As this occured in May, before the start of the swarming season, it would have been especially interesting. for the swarm would have had to have been an overwintered colony and such cases have not been described in apicultural literature as honey bees don’t live in the ground, nor in clay, at all. But the bees from underground were not honeybees - they were Osmia rufa bees, but these bees don’t live in colonies. Careful observation of the bees showed that all the bees flying out had the lumps of clay in their mandibles. The reason for this phenomenon was very simple. That year the spring was extremely dry and osmia bees had problems obtaining wet clay which they usually use for the building of partitions between cells and for the sealing of the entrance to the nest. Osmia bees from surrounding localities had discovered a common clay-mine and were able to make use of the wet and soft clay which was underground. This case is just one example of to show the abundance of osmia bees in favorable localities. 
My first meeting with osmia bees took place in childhood near the reed stem roof of an old shed. These lovely bees worked busily and sealed the ends of the tubes with clay or even mud. A second close meeting was in my own small-scale queen breeding station. I had invented extra-multiple mating hives and used these hives only in this apiary (see the previous issue of BKQ, #81, pages 44-46). Common feeders are an important feature of these hives and 10 mm splits were an essential component of these feeders. The populating of the mating hives with honey bees usually occurred after the fruit trees had finished flowering - ie, at the end of the osmia season. Because of this I had problems with osmia nests in my mating hives every year: the feeder gaps were choked up with osmia bee cells. For several years I was forced to destroy the osmia bee cells in my feeders. As an entomologist I was sad to do this as I hadn’t any other option at that time. However, I have now found a solution by placing special osmia bee traps in the slots or gaps in my mating hives. These were simply designed devices with 6 -10 mm spaces between two parallel plates, one of which could be glass. (Fig.2). These osmia “observation hives” were used by osmia bees very well. The filled osmia traps (with clay partitions, pollen and larvae) were removed from the apiary to my balcony in my town apartment, were I have a small osmia apiary as a hobby (Fig.1).
 

Fig.1. The osmia bee hobby apiary on the balcony of a second floor apartment. The observation osmia glass /plywood slots iare in the lower part of the photo. The boxes with reed tubes are in the upper part. The beautiful red-black Osmia cornuta bees prefer the reed tubes and the Osmia rufa bees’ nests can be found in the tubes and in the different artificial slots.

All these bees were Osmia rufa only. Later I added some very beautiful Osmia cornuta bees from the southern localities. These bees prefer to make their nests in the reed tubes only and used the “osmia observation hives” only rarely. 
The famous Ukrainian osmia bee scientist, Dr B Zinchenko, created large scale osmia apiary in the Poltava region. He started osmia bee rearing in 1973 from 110 cocoons and increased the population during 18 years to 5 million cocoons. The coefficient of multiplication changed from 0.79 in bad years to 6.26 in favourable ones (the average for 18 years was 1.8). The largest quantity of osmia bees was nearly 5 million at his apiary. This is the same quantity of bees as you will find in May in an apiary of 200 - 250 honeybee colonies. A technology for the large scale rearing of osmia bees was developed and methods were devised to overcome their various illnesses and parasites. Unfortunately, Dr Zinchenko had none of his work published in English and his sudden death almost stopped any further progress in this very interesting kind of beekeeping. His death coincided with the collapse of the government’s financial support of science in Ukraine and now we have the small osmia apiary instead of the large one in the Poltava region (see fig. 3) and no scientific investigations are taking place.
 

	Fig.2. Osmia cocoons in the two “osmia bees observation slots or osmia bees “observation hives”. It is possible to see dead larva which have been damaged by different parasites. Several bees fill one observation hive, in each tube every bee has its own nest. It is also possible, with these, to see the results of rearing after the end of osmia activity and even to observe the larvae’s growth.
	Fig. 3. Blocks of 15 boxes with reed tubes for osmia bee rearing in the Poltava region. More than 20,000 reed tubes are in the field of view. 3 such blocks was populated by osmia bees in 2005 , two species of osmia bees (O.rufa and O.cornuta) live in tubes together and the cocoons which are marketed are usually a mixture of the both species

 The osmia bees reared in this apiary are sold - the usual customers being the owners of small glasshouses or polytunnels who grow cucumbers and where the use of honeybee colonies for pollination is relatively expensive. Honeybee colonies in greenhouses need special management whilst the use of osmia bees is extremely simple and doesn’t demand any special knowledge. During the five years between 1986 and 1990, more than 3 million cocoons were sold to more than 500 customers. Now less than one hundred thousands of cocoons appear on the market every year. However, during the last several years, including this 2005 season, conditions were unfavorable for osmia rearing and the coefficient of the years’ cocoon multiplication was low - just slightly more than 1. The use of these bees for pollination is restricted now to greenhouses where cucumbers are cultivated.
However, Ukraine has an enormous potential for the rearing of osmia bees and the experiments of the late Dr B Zinchenko support this conclusion. Several Ukrainian honey beekeepers, though, have the bands of reed tubes for osmia bees as decorations in their honeybee apiary. This is becoming a modern fashion ever since the publication of one beekeeper’s work about the nice black-red bees like bumblebees. It is possible to see such bees even in the private apiary of President of Ukraine Victor Yuschenko!

It is possible to see more information about the rearing of Osmia bees in the UK, in Matthew Allen’s “Working with the Oxford Bee Company” Bee Biz, 2003, #16:23-27. Christopher O. Toole’s “The Red Mason Bees”, (2000, 35 pp) an important handbook on the subject, is also available from Northern Bee Books. Editor.