It is more difficult to adjust the temperature of a nest in open space than a nest within a closed space. Therefore, it has been thought that the existence of nests in open space is very rare. However, nests in an open space are seen frequency in an urban area. Temperature control of nests in open space is done as follows.

A nest made in open space (summer)	A nest made in open space (winter)

In the summer, honeybees in a nest in open space adhere closely on the surface of the nest, leaving a small gap between them.
The nest cannot be seen. The whole nest looks like a bee ball. When compared with the same nest in the winter, a large difference is seen.. The summer bee is quiet and has almost no motion. The bees which have come back to the nest, go into the center of the nest. Many bees lessen generation of heat by not working at all, and seem to be passing the hot summer.
In the winter, the bees crowd into the lower part of the nest. Compared with the summer, the bees do not separate from one another but instead overlap each other. This seems to be a behavior which does not waste internal heat. Since the temperature falls below the freezing point in the cold morning, heat is taken from the bee on the surface of a nest. The bees cannot move if it becomes　below 10 ℃ in body temperature. In order to avoid this, the bees change places, and in doing so generate heat at the same time. In the summer, the surface of the nest is quiet, but in winter it is noisy caused by the bees which come out a nest, and those which go inside. It seems strange that the nest is livelier in the winter.
In a nest in an urban area, brood nest is made in midwinter too. As the brood nest is in the under part of a nest, the bees keep the nest temperature at 35℃ throughout the winter. In order to maintain this temperature, the temperature of the bees which are present in the brood nest area, is about 35℃. Because the under part of a nest could not be touched by hand, the temperature was measured by thermography. The highest body temperature of a bee was 36.1℃ (the ambient temperature at this time was 6.7 ℃). Surely, if we touched the nest, it would have felt warm. A picture shows that the thorax temperature of a single bee is higher by 2 ℃ than the abdomen temperature. This is the reason that a bee produces heat using the thorax muscles, and the bee has the body structure where heat does not travel across the thorax to the abdomen. The abdominal temperature is lower than the thorax temperature.

Temperature measurement by thermography (Measured on February 1, 2000.Ambient Temperature of 6.7℃ )

The warmest place is 35.8 ℃ (enlargement).(enlargement)	P1.P2 shows the thorax and abdomen of a bee (enlargement)

[Acknowledgement] I appreciate "Kashimura" Osaka Branch who lent the thermograph equipment. (The price of thermography is high - no less than 4 million yen).

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