they return. By removing roadblocks, V. rufa would be able to enter and exit more smoothly. Light intensity The amount of light present in the morning or evening is most critical element affecting wasp movement. In the evening, light intensity plays a key role in determining the time that the last movements to and from the nest occur. For V. rufa, the minimum value for sorties to leave the nest in the morning is 4.0 lux or 0.37 ft cs. The amount of light required for the last sorties to return to the nest is 6.0 lux or 0.56 ft cs. The level is related to the compound eye length, 2.4 mm in this species. For comparison Vespa crabro (the European Hornet) has a much larger body and thus a greater eye length of 3.7mm enabling it to forage in moonlight at 0.2 lux. Temperature If the temperature is too low, then wasps will not leave the nest. There has not been sufficient research on this topic, but the current research suggests very different temperatures for different species. Presence of other wasps Whether there is another wasp present at the exit to the nest will affect V. rufa decision about leaving the nest. For V. rufa, "five wasps must be present to act as a 'releaser' for foraging." Only when there are insufficient insects in the nest entrance can wasps passing in the opposite direction serve as releasers. This phenomenon of "social facilitation" means that V. rufa leave nests in clusters rather than in a continuous trickle. The releaser behaviour pattern of V. rufa is more readily noticeable than that of other British species. Orientation flights When a young worker leaves the nest for the first time, it will generally make 2 to 3 'orientation flights' in order to familiarise itself with the entrance to the colony amidst the surrounding landscape. In the first flight, the worker flies approximately 25 cm out of the nest at once and then quickly turns around to face the entrance. The wasp slowly flies back and forth to the nest several times, surveying an angle that is approximately 90 degrees, while facing the entrance. Then, the wasp promptly returns to the nest, the whole flight lasting only about one minute or less. Soon after returning from the first flight, the wasp will leave the nest in a similar fashion, but this time ventures out approximately 15 to 20 meters and covers an angle of approximately 280 degrees. Once 2 meters away, V. rufa'' will fly back and forth repeatedly in a figure-eight pattern, while facing the entrance to the nest. In some cases, after this second flight the wasp will have gathered all of the knowledge necessary to fly off. Other wasps must make a third orientation flight that is like the second one. At first, the worker may miss the entrance to the nest many times; however, after six to twelve trips, the wasp gains its bearings; flights become longer, and reentry into the colony becomes more precise. References Category:Insects described in 1758 Category:Vespidae Category:Hymenoptera of Europe Category:Taxa named by Carl Linnaeus