Seasonal Change of Flight Ability of Cletus punctiger (Heteroptera : Coreidae)

Abstract

Techniques of tethered flight and fight mill were used to investigate the seasonal change of the flight adility of Cletus punctiger. Bugs caught in the field flew for about 2hr continuously in both techniques and the maximum flight velocity was estimated at about 45 m/min on the average in the filght mill technique. These results, in addition to its wide range of hosts, seem to indicate that flight of this species is the "appetitive" type which means that the insect does not migrare long-distance like brown planthopper Nilaparuata lugens but fies about from one host plant to the next. The proportion of good fliers decreased gradually in summer, that is, the proportion of bugs flying for one minute or more being 70% in early to mid June decreased to 25% in July to August tested by the tethered flight and from 60% to 10% by the fight mill. The longest continuous flight time of individual bugs was also shortened. Therefore, the decline of flight ability was considered to be one of the reasons for rare immigration of about bugs to late-heading rice fields.