Ladybirds are common beneficial predators that feed primarily on a aphids in Australian cotton crops. Predation by ladybirds Helicoverpa spp. eggs has been observed, however the relationship between predator density, egg density, aphid availability and habitat size has not been investigated. Under laboratory conditions three banded ladybirds were the most effective egg predators and variable ladybirds the least effective of the four ladybird species tested. In greenhouse experiments three banded and variable ladybirds showed similar predatory capability and under natural conditions variable ladybirds may be the most effective coccinellid predators of Helicoverpa spp.