Egg weights and total eggs produced by nine Speyeria spp. (Nymphalidae) in California allowed estimates of per-egg and lifetime reproductive effort. Interpopulation reproductive effort in four species and intrapopulation reproductive effort of two species in different years were documented. Female body weight was uncorrelated with either individual egg weight or total lifetime egg weight. Smallest eggs (mean dry wt/egg = 0.05-0.06 ug), and the greatest number of eggs, were from S. coronis (Skinner) and S. zerene (Boisduval) whose females undergo summer reproductive diapause in dry habitats. Largest eggs (mean dry wt/egg = 0.10 ug) were from S. nokomis (Skinner), a wet habitat species. The greatest relative reproductive effort was made by dry habitat species lacking reproductive diapause. Reproductive effort and duration of first instar exposure to summer temperatures were positively correlated. Intrayear variation in total egg weight did not vary significantly among populations of S. callippe (Boisduval), S. hesperis (Boisduval), S. nokomis, or S. zerene but mean total egg weights were significantly different in females from the Donner Pass, CA population of S. mormonia (Boisduval) in two years. S. zerene from high elevations lacked the reproductive diapause characteristic of lower elevation populations. The reproductive strategies of Speyeria spp. are adaptive responses to the desiccation stress that their habitats impose on diapausing first instars.

Egg weights of Speyeria (Nymphalidae) species from California were measured to estimate relative sizes of first-instar larvae. First-instar larvae were compared for diapause intensity and for their physiological and behavioral responses to atmospheric humidity and free water. Diapause intensity, measured by number of days between first instar and molt to second instar, ranged from 7.6 d (Speyeria nokomis) to 40.7 d (Speyeria callippe). Among species, diapause intensity was uncorrelated with egg weight, but within three species (S. nokomis, Speyeria mormonia, and Speyeria zerene), diapause intensity was positively correlated to egg weight. There was significant interspecific variability in the desiccation tolerance of diapause larvae to low (11% RH) humidity. The least and most desiccation-tolerant species, respectively, were S. nokomis (LT50= 1.9 d) and S. callippe (LT50 = 13.6 d). Interspecific desiccation tolerance was uncorrelated with egg weight. Larvae of S. nokomis moved from lower to higher humidity within a humidity gradient, whereas larvae of S. callippe did not move toward higher humidity. Desiccated larvae of S. callippe and S. zerene rehydrated by imbibing free water. Exposure of S. callippe and S. zerene larvae to 100% RH in the absence of free water did not result in a body weight increase, but high humidity conditions reduced the rate of water loss. © 2014 Entomological Society of America.