Catalpa Sphinx (Ceratomia catalpae), Newark DE. August 2018.
This is a species that, from a personal observation, relies heavily on the numbers game.
Females lay masses of eggs on their host plant (Catalpa sp.) in the hundreds, and caterpillars feed gregariously (together) on the leaves that are available. In the south, they can defoliate catalpa trees on occasion, but it is not food that limits this species. It is the pressure of predation: birds, predatory wasps, and species of parasitic wasps will either eat or lay their eggs in the caterpillars to prevent a rise to adulthood.Culturally, people have even used the caterpillars as catch fish, with mature larvae (around 2-3 inches, or 5-8 cm) easily viewed as juicy, black-and-yellow bait against the green background of their host plant.
In contrast, the adults appear more like tree bark, allowing them to blend into the background of a forest so it can spend its few precious days finding a mate (the adults do not feed).
This moth I reared from a batch of 15 caterpillars off of a southern catalpa plant (Catalpa bignonioides). This was the only one that reached adulthood, with the rest becoming hosts for many parasitic wasps (pictures to come when I find them again). At least two generations in the Mid-Atlantic, with caterpillars overwintering as pupae in the soil.