The evolutionary interests of any two individuals are rarely, if ever, identical. This must be true, simply because they do not share the same allels for all loci. Where alleles at a locus differ, there will be competition among them. Because males and tmales, by definition, produce gametes of different size (anizogamy), they typically maximize their reproductive success in more or less different ways. Whenever selection favors different values for a phenotypic trait in males than in females, there is potential for intragenomic (intralocus) sexual conflict. Intragenomic conflict will ppear in all those cases where the direction of selection at a given allele depends upon in which sex it resides (i.e., whenever there is a sex-genotype interaction for fitness). Sexual selection guided by male-female conflicts of interest can result in resolvable evolutionary chases that tend to be unending. It has been reported that in many insects mating involve high costs to females (increased predation risk and energetic expenditure) but few, if any, balancing direct benefits. Sperm-displacement rates are high, and males thus gain from rematings. Mating frequencies are high; males mate multiply for reasons of convenience. In many species, inclouding waterstriders (Heteroptera: Gerridae) males are considered to have won’ the evolutionary conflict over the mating decision in the sense that they have made acceptance of superfluous matings ‘the best of a bad job’ for females, by evolving behavioral and morfological traits that make it costly for females to reject males attempting copulations. Females, however, have apparently evolved a variety of counteradaptations to make males harassmnet, to gain control over mating.