Breathtaking Metamorphosis: The Saturniidae Moths..

Some saturniids are strictly univoltine, producing only one generation a year, whereas others are multivoltine, producing more than one brood a year. Spring and summer broods hatch in a matter of weeks; autumn broods enter a state known as diapause and emerge the following spring. How the pupae know when to hatch early or hibernate is not yet fully understood, though research suggests day length during the fifth larval instar plays a major role, as well as cooling temperatures.