Demography and Behavior of the Damselfly, Argia Apicalis (Say), (Odonata: Coenagriidae)

Abstract

Demography, movement to and from water, reproductive behavior, behavior, localization, and spacing of single males were studies. All marked and unmarked individuals at water were counted on 47 consecutive days and hourly on three days. Simultaneous counts were tallied at pond and in a roosting area on nine days of varied weather. Behavior of 33 pairs, seven observed constantly from seizure until female left the pond, and of 17 unpaired males, each constantly observed for 30 min, is presented. Daily counts of matures and occurrence of tenerals throughout indicated a summer species and a population of diverse age. Mean minimum reproductive age for males were 8.4 days, for females 7.0 Maximum activity was near noon. Males were at water on 44% of their days lived, females on 20%. Repeat matings during the same day were very rate in both sexes. Males mated on 20% of their days at water, females on 89%. Because of this reciprocal relationship between frequency at water and frequency of mating, the mean total number of matings for both sexes was approximately equal. Movement from roosting area to pond was characterized by random shifting. Males arrived at water earlier than females and became spaced at six—foot intervals. Males recognized kind and sex and seized either flying or perched females immediately when they arrived without courtship or display by either sex. Copulation and oviposition were at sites other than those defended earlier in the day by the unpaired male. Copulation was a short distance away from the main concentration of single males and lasted 16 min. Ovipositing females were gregarious and single males tolerant of pairs, so that egg laying occurred at a few communal sites: willow roots, boards and sticks, horizontal Helenium. Egg laying consisted of three sequential phases: exploration (25 min), oviposition in tandem (65), oviposition alone (21). The male was the active partner in seizure and copulation, the female in oviposition. Most females avoided a second seizure during the same day by rapid escape flight if captured a second time, copulation of oviposition was unsuccessful. A particular male was not associated with a particular six—foot interval from day to day, but in any one day, most males remained within the same interval for 76% of their total time at water. They maintained these areas by aggressive activity which was in no way sexual and which warded off 87% of all intruders. Most important were strong flights toward intruders without physical contact and patrols of an area.