Insect Swarming and Mating

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Abstract
Insect mating swarms are characterized by the simultaneous flight of numerous males and the initiation of copulation while in flight. In dispersed swarms, males are distributed through an area and intercept flying females. Swarms consist of males flying at particular stations, often at a conspicuous object (the swarm marker), and usually in aggregations. It is logical that females are attracted to these swarms, but accidental interception has not been disproven. Swarms may result from intersexual selection, and females approach swarms to choose and mate with males that are of high genetic quality or that will invest in their progeny. Alternatively, females may only fly to swarms as a last resort, if they require insemination and the cost of waiting to be found by males exceeds the risk of searching for swarms. The shape of swarms presumably results from marker size, the number of participants, and the heights of approaching females. Changes of swarm height and associated changes of shape are probably due to perceived or probabilistic changes in the availability of females at various heights. The time of swarming may be most strongly influenced by predation and climatic factors. Male flight between swarms may maximize mating success by providing for evaluation of competition and female availability at various swarms. The major influence on flight patterns of swarming males is probably mating competition. Loops, zigzags, and figure 8''s are common male motions that seem suited to monitoring the swarm periphery for arriving females. Mayflies and Nemopteridae have a pendular, rising and falling flight in swarms. Female arrival at swarms sometimes causes changes in male flight. Swarms consisting mostly or entirely of females result from a variety of factors.