Behavioral Ecology and Sociobiology

, Volume 25, Issue 4, pp 255–260

Protandry in western cicada killer wasps, (Sphecius grandis, Hymenoptera: Sphecidae): an empirical study of emergence time and mating opportunity

  • Jon Hastings


Sphecius grandis is a univoltine, colonial wasp. Females mate once and are sexually receptive when they emerge in July and early August. Males generally emerge earlier in the summer than females. The opportunity for each male to acquire mates is a function of the number of females emerging during his lifetime and the number of competitiors that are active when the females emerge. I determined a mating opportunity index (MOI) for each male in an aggregation of wasps for three separate summers, and correlated the MOI of individual males with their emergence date. The MOI of a male estimates the potential contribution that timing of emergence makes to his reproductive success. In 1984 males emerging near the mean of the male emergence distribution had the highest MOI. These males emerged between one and two weeks prior to the mean female emergence date. However, in 1981 late emerging males had the highest MOI. In 1983 there was no significant difference in MOI among males. As a result of between-year variation in female emergence schedules and in the duration of male lifetime, the selection pressures influencing male emergence time vary between years.


Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.


  1. Alcock J (1976) The behavior of western cicada killer males, Sphecius grandis (Hymenoptera: Sphecidae). J Nat Hist 9:561–566Google Scholar
  2. Dambach CA, Good E (1943) Life history and habits of the cicada killer (Sphecius speciosus) in Ohio. Ohio J Sci 43:32–41Google Scholar
  3. Darwin CR (1871) The descent of man, and selection in relation to sex. John Murray, LondonGoogle Scholar
  4. Emlen ST, Oring LW (1977) Ecology, sexual selection, and the evolution of mating systems. Science 197:215–223Google Scholar
  5. Evans HE, West-Eberhard MJ (1970) The wasps. University of Michigan Press, Ann ArborGoogle Scholar
  6. Gwynne DT (1980) Female defense polygyny in the bumblebee wolf, Philanthus bicinctus (Hymenoptera: Sphecidae). Behav Ecol Sociobiol 7:213–225Google Scholar
  7. Hastings J (1986) Provisioning by female western cicada killer wasps, Sphecius grandis (Hymenoptera: Sphecidae): influence of body size and emergence time on individual provisioning success. J Kansas Entomol Soc 59(2):262–268Google Scholar
  8. Hastings J (in press) The influence of size, age, and residency status on territory defence in male western cicada killer wasps (Sphecius grandis, Hymenoptera: Sphecidae). J Kansas Entomol SocGoogle Scholar
  9. Iwasa Y, Odendaal FJ, Murphy DD, Ehrlich PR, Launer AE (1983) Emergence patterns in male butterflies: a hypothesis and a test. Theor Pop Biol 23:363–379Google Scholar
  10. Nielsen HT, Nielsen ET (1953) Field observations on the habits of Aedes taeniorhynchus. Ecology 34:141–156Google Scholar
  11. Richards OW (1927) Sexual selection and allied problems in insects. Biol Reviews 2:298–364Google Scholar
  12. Thornhill R, Alcock J (1983) The evolution of insect mating systems. Harvard University Press, CambridgeGoogle Scholar
  13. Wiklund C, Fagerstrom T (1977) Why do males emerge before females? A hypothesis to explain protandry in butterflies. Oecologia 31:153–158Google Scholar

Copyright information

© Springer-Verlag 1989

Authors and Affiliations

  • Jon Hastings
    • 1
  1. 1.Northern Kentucky UniversityHighland HeightsUSA

Personalised recommendations