Most moths are nocturnal and prefer to fly around at night. These moths rest in an out-of-the way place during the day. There are some moths that are active during the day; they are known as diurnal moths.
Butterflies and moths are genetically similar insects. Generally, being active at night is considered a criterion for being a moth. However, there are some physical differences between butterflies and moths, and there are a few species that have all of the physical characteristics of moths but behave diurnally. One interesting commonality between both types of insects is that they do not have eyelids.