Most species normally take 5-10 days to emerge from the pupae. Habitat Agonum quadripunctatum, a forest species, is a good flyer and is attracted to smoke, whereupon it lays its eggs in recently burnt areas. Many polyphagous species such as Harpalus spp. Depending on habitat, density fluctuates from 1-1000 per m 2 at overwintering sites. Nocturnal species are normally larger.
Diurnal species are iridescent while nocturnal species are duller.
Forest beetles are generally nocturnal whilst grassland species are diurnal. In hotter areas the nocturnal habit is more common. Within a species population you can also have variety e.g. with Carabus auratus some are nocturnal, some are diurnal, and some have no diel preference. Moulds and desiccation are the primary egg killers, while dehydration, starvation and predation are the major causes of death for larvae and pupae. It has also been shown that the heavy predation pressure of small mammals experienced in many habitats, reduces both population numbers and species diversity.