Abstract
In the armyworm, Pseudaletia separata, males emerged from crowded larvae produced larger spermatophores than males from solitary larvae, despite the fact that the adult body weight was not different between the 2 types. Spermatophore size increased with male age or time interval between the previous and current matings. Male body size, female body size and mating duration did not affect spermatophore size. Biological significance of the difference in spermatophre size between solitary- and crowded-type males is discussed.
