A search for behavioural variation in first and last laid eggs of western tent caterpillar and an attempt to prevent a population decline

Abstract

Earlier studies of western tent caterpillars reported that female moths deposit eggs so that the first eggs are laid at the top of the mass on a sloping branch. The first laid eggs are described as having greater nutrient stores and producing more active larvae. Based on these descriptions, field tests were conducted in which 'active' tent caterpillar groups were constructed by combining the first laid halves (upper halves) of two egg masses and 'less active' groups composed of the last halves of the egg masses. Contrary to expectation, the groups of caterpillars arising from first laid eggs had neither better success nor did they produce larger tents than the last laid eggs. Laboratory behaviour tests conducted concurrently showed that unlike earlier studies, larvae from first and last laid batch halves were equally active in this population.