A single cockroach can supply thousands of nematodes for the next generation. Spiders, toads, frogs, other insects and small mammals feed on a wider array of items, cockroaches of which are only one. There is, however, a large species of spider found throughout Florida that feeds almost exclusively on cockroaches. One unifying characteristic of all cockroach natural enemies is their susceptibility to toxic pesticides. In most animal species there exists a few individuals which are resistant.
Pesticides kill off the susceptible majority and leave only the resistant few.
As these resistant few breed the gene for pesticide resistance increases and thus in each subsequent generation a greater majority of individuals are resistant. The phenomena of resistance development can occur only if the population is targeted, as are cockroaches, as a pest. Since beneficial insects are not normally considered pestiferous, they are not the target of insecticide application and do not normally develop resistance. Preservation and perpetuation of the complex of cockroach natural enemies depends heavily on the non-use of pesticides. Silica gel is simply finely ground sand or glass that rubs the protective waxes off the cockroach cuticle resulting in cockroach dehydration.