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| ... sphere is sealed with wax. The queen then forms a small tub of wax, puts pollen in it and then lays 5 to 15 eggs on the pollen. It also builds a second, slightly larger vessel for nectar (for food on rainy days) . In the period up to August the population of the colony grows from 60 to 150 animals. During the months of September and October the colony (with the exception of the queen) dies. | | |
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| Some years, the silver Y appears en masse and can cause great damage to crops. This population increase is due to migration. The silver Y is active from February to December. | | |
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| Philanthus triangulum are widespread in the northern hemisphere, but rare due to strong natural fluctuations in population and the use of pesticides in agriculture. Under favourable conditions, this species reproduces twice a year. | | |
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| The tawny mining bee is commonly found from Western Europe and southern Scandinavia to the Balkans. This species reproduces once a year and despite having low population densities in some places, is not regarded as endangered. | | |
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| Anthocharis cardamines are commonly found throughout Europe and Asia up to the polar circle, as well as in the Middle East. Their population has significantly increased in the last 30 years in Western Europe especially in Scotland and Ireland, this is attributed to climatic changes.However this species is in decline in Central Europe. Although numerous biotopes have been lost due to ... | | |
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| Vespa crabro reproduce once a year. As a social wasp, it counts among the colony building insects. The colony has a life span of one year. The population comprises 100 to 700 (in extreme cases up to 1000) hornets. | | |
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| ...colony which resembles the pecking order amongst chickens and this can create aggression, which leads to more or less heavy fighting between individual female workers. When this happens workers may sting each other resulting in deaths. If the population of the nest expands greatly and there is no room for further development all the hornets move to a more suitable place and establish a new nest (branch formation). | | |
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| ...n autumn the young queens and drones hatch. In late September or early October the drones start fightings between themselves in order to fertilize the young queens. While the fertilized queens find hiding places to overwinter , the remainder of the population dies with the first night frosts. | | |
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| The rove beetle (Velleius dilatatus) is a constant co-inhabitant in the hornet nest. Its stay does not unfavorably affect the population of the nest. | | |
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| Excentricus planicornis are widespread from Western and Central Europe to southern Scandinavia and North Africa. In Germany, this species is common. The size of the current population is difficult to gauge, because this species is not sufficiently discovered. In Bavaria, the species is accepted as at risk. In the "Red List" (a list of endangered species) of Bavaria. | | |
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