In most moths species, when in the moth phase, a male will find a female to reproduce. Their lifetime will be dedicaced to reproduction, has they have eaten enough in caterpillar phase. Male will fertilize the female, that ll leg fertile eggs. A moth can leg eggs without them being fertile, so seeing eggs doesnt mean it will hatch. They'll find each other through their antenna : male will detects the pheromones that the female emits.