Why are some moths flightless?
Flight offers many advantages, but is hard work. This is why some birds and many insects have given it up. At least 25 families of moths have either small wings or none at all. Often only the female moths become flightless, leading to striking visual differences between the sexes. In temperate climes, many flightless moths fly in winter, so their flight loss could partly be an adaptation to low temperatures and strong winds, both of which make flying more challenging. The females release chemical pheromones to attract males, and instead of maintaining flight muscles can devote more energy to reproduction. But why be active in winter at all? It could be because fewer predators are around. However, there are always exceptions. One is the vapourer moth – the orange-brown males flit erratically around British treetops from July to September, while the curious, near-wingless females stay on the trees.