 Controlled-breeding experiments with the cricket "Gryllus firmus" demonstrated inbreeding depression, as nymphal weight and early fecundity declined substantially over the generations' this was caused as expected by an increased frequency of homozygous combinations of deleterious recessive alleles.Crickets have many natural enemies and are subject to various pathogens and parasites.They are eaten by large numbers of vertebrate and invertebrate predators and their hard parts are often found during the examination of animal intestines.