Protandrous Arrival in a Population of the Periodical Cicada Magicicada septendecim (Linnaeus) (Hemiptera: Cicadidae) in Montgomery County, Maryland.

Differences in number and arrival time of male and female adult periodical cicadas, Magicicada septendecim (Linnaeus), Brood X, in a small geographic area of Maryland in 2004, are described and discussed. Newly emergent cicadas were counted, by sex, along various suburban streets. A probable incidence of protandry--the arrival of adult males before adult females--was observed. Data analyses by test of proportions show that for some of the first days of counting, in one of the two sample sites and in both sites combined, the disproportionate appearance of adult males was statistically significant, while for the last few days, the disproportionate appearance of adult females was also statistically significant. In one of the two sites and in both sites combined, significantly more females than males for the season as a whole were also observed. Though this study appears to confirm previous findings, there is little discussion in the literature on protandry in periodical cicadas, and no other study on this subject and species with detailed methodology for sampling, that avoids double counting. It might be useful to conduct field counts of periodical cicadas in other locations to discover where such protandry may or may not occur. It is believed that this mode of protandry is adaptive for the species, and that it evolved to enhance survivability or reproductive opportunity for both sexes. [ABSTRACT FROM AUTHOR]