Caterpillar basking behavior and nonlethal parasitism by tachinid flies

Insects that become parasitized may behave differently than unparasitized individuals. For instance, some parasitized caterpillars bask at the top of vegetation. Caterpillars of Platyprepia virginalis that had previously been infected by the tachinid parasitoid, Thelaira americana, were more likely to bask on dead vegetation than Mere unparasitized caterpillars. This behavior was associated with elevated body temperatures compared to individuals that were not basking. This is the first report of behavioral fever by a caterpillar, by any insect in the field, ard by any insect caused by a macroparasite rather than a pathogen. The results are consistent with the hypothesis that parasitized caterpillars are induced to develop behavioral fever by basking and this may help them recover from their parasitoids; other interpretations are also possible.