Concealment behavior of nymphs of <i>Blaberus gigan­teus</i> L. (Dictyoptera: Blattaria) in relation to their ecology

Abstract

Nymphal Blaberus giganteus (L.) tend to hury themselves or hide in (revices whenever possible, whereas adults do not do so to any great extent. Burrowing of both adults and nymphs takes place significantly more in light than in darkness. Nymphs are photonegative at ali times; adults only during the nocturnal phase of their circadian rhythm. Adults avoid crevices in dark, but show neither avoidance nor preference for them in light. Nymphs, on the other hand, show a positive reaction to crevices in both light and darkness, but the response is significantly greatee in light. Transpiration rates and "critical" cuticular temperatures are essentially the same in both adults and nymphs. The nymphal cuticle is probably more resistant to water loss at higher temperatures than that of adults. We conclude that concealment behavior in nymphs is probably correlated with escape from predators rather than with physiological factors because, unlike the adults, the nymphs do not produce offensive odors and their tibial spines are less sharp.