Cockroaches : their biology, distribution and control

Overview

Cockroaches are an ancient and highly successful form of insect life. They have been in existence since Pennsylvanian (Upper Carboniferous) times. The fossil record indicates that they achieved an optimum body form early in their evolutionary history and have remained a very stable group since that time (Moore et al. 1952). Figure 1 is a photograph of a 250 million-year-old fossil insect that is easily recognizable· as a cockroach. About 3500 species of living cockroaches have been catalogued (Princis, 1962-1971), but additional species and even new genera are being found and named (Roth & Princis 1971, Roth 1973, 1985, 1989, 1990a, 1990b, 1991a, 1991b, 1991c, 1992, 1993a, 1993b, Fisk & Schal1981, Grandcolas 1991, 1994a, 1994b, Peck & Roth 1992). Wolda et al. (1983) reported that 42% of the species they collected at light traps in Panama were new to science. Thus, the final number will probably far exceed the figure of 4,000 suggested by James & Harwood (1969).

Rehn (1945) pointed out that the majority of cockroach species are not domiciliary pests. In fact the important pest species constitute less than 1.0% of all known cockroach species. The remainder are free-living insects that are found mainly in the tropical regions of the world. They live in a wide variety of situations such as among or under dead or decaying leaves, under the bark of trees, under rubbish or stones, under drift materials near beaches, on flowers, leaves, grass, or brush, in caves or burrows, boring in wood, in the nests of ants, wasps, or termites, or in a semi-aquatic environment (Roth & Willis 1960, Roth 1973). In contrast to the nocturnal habits of most common domiciliary-pest species, many other species are diurnal. Thus, the layman's view of cockroaches, which is based on experience with the few domiciliary species, is unrepresentative of the group as a whole. Indeed, some of the tropical forms are strikingly beautiful insects.