Imperial Moth

The wingspan of an adult is between 80 and 175 mm (3+1⁄8 and 6+7⁄8 inches). There is a high amount of variation within this species. The colors of the adult are always primarily yellow with red, brown, and purple blotches but can vary distinctly on this. Light and dark morphs of this species are found in both the northern and southern regions of their range. Individuals from the northern regions of their native range may tend to have fewer dark markings. Larvae can be small (approximately 10–15 mm long) and orange with black transverse bands and large spines in the first instar, to 3–5.5 inches (75–100 mm) long in the fifth instar with long hairs and shorter spines and color morphs varying between dark brown and burgundy with white spiracle patches, and green with yellow spiracle patches.

Imperial moths (their many regional morphs, subspecies, and sibling species) range from Argentina to Canada and from the Rocky Mountains to the Atlantic Coast. This species is the widest-ranging and northernmost in its genus Eacles. Nominate Eacles imperialis imperialis has been recorded historically from New England and southern Canada, south to the Florida Keys, and as far west as Nebraska. E. i. imperialis may not appear in Massachusetts today except for a population located on Martha's Vineyard. The true northern limits of the nominate's range are unknown because of possible confusion with subspecies E. i. pini in existing records. Subspecies E. i. pini occurs in coniferous and transition zone woodlands at the northern edges of the New England and Great Lakes States and northward into Canada. In the southwest, it is replaced by the closely related E. oslari. Other subspecies are found in Mexico and South America. Subspecies E. i. magnifica can be found in Brazil and surrounding regions.

In Florida and other southern areas, a few adults emerge in spring or early summer, but most emerge in late summer. There is only one brood a year. Imperial moth larvae are polyphagous with many recorded hosts. However, there are probably regional differences in food preferences. The following plant species are the most commonly reported hosts for the imperial moth: pine species, maple species, oak species, sweetgum, and sassafras.

Egg. The female will lay eggs at dusk. It will do so either singly or in groups of two to five on either side of a host plant leaf. The eggs hatch in roughly ten days to two weeks. Newly hatched larvae will eat the shell of the egg they emerged from.

Larva. At the end of each instar, a small amount of silk is spun on the major vein of a leaf. The larva then latches onto the silk with its anal claspers and prolegs and begins to molt. It first becomes dormant and undergoes apolysis, then after an additional day or so, undergoes ecdysis. The larva emerges from its old exoskeleton, puffs up, and hardens as it enters the next instar. This species will sometimes eat the old exoskeleton for protein nutrition. Similar to many other Saturniidae larvae, the imperial moth has five instars. First instar

The first instar generally lasts a short period of time. …