What you’re looking at is a saturniidae moth caterpillar. The Saturniidae family contains the biggest moth species, which have hefty bodies coated in hairlike scales, lobed wings, shortened mouthparts, and tiny heads.
Adults have wide, lobed wings, hefty bodies coated in hair-like scales, and smaller mouthparts. They lack a frenulum, yet the hindwings overlap the forewings to provide the illusion of a continuous wing surface.
Saturniids feature translucent eyespots or “windows” on their wings that are occasionally vividly colored. Males have bigger, wider antennae than females, however sexual dimorphism varies by species.
The majority of adults have wingspans ranging from 1-6 in (2.5-15 cm), however certain tropical species, such as the Atlas moth (Attacus atlas), may have wingspans of up to 12 in (30 cm). Saturniidae, along with certain Noctuidae, has the biggest Lepidoptera and some of the largest insects alive today.
The majority of saturniid species are found in woodland tropical or subtropical areas, with the highest diversity in the New World tropics and Mexico, however they are found worldwide. There are around 12 documented species in Europe, one of which, the emperor moth, is found in the British Isles, and 68 recognized species in North America, 42 of which are found north of Mexico and in Southern California.
Some saturniids are strictly univoltine, generating only one brood per year, whilst others are multivoltine, producing many broods every year. Spring and summer broods hatch in a couple of weeks, while fall broods enter diapause and emerge the next spring. The pupae’s decision to hatch early or hibernate is not entirely understood, but research shows that day duration during the fifth larval instar, as well as lowering temperatures, have a significant effect.
Longer days may cause pupae to develop earlier, whereas shorter days cause pupal diapause. The number of broods is variable, and a single female can have both fast-developing and slow-developing offspring, or she might have a different number of broods in various years or portions of the range.
Spring and summer broods differ in several species; for example, the two Saturniinae species Actias luna (the Luna moth) and Callosamia securifera both contain specific genes that may or may not be triggered depending on environmental circumstances.
We don’t know why the caterpillars have such a complicated look. This is how they seem after the transformation:
Saturniid caterpillars are thick, cylindrical, and big (50 to 100 mm in the final instar). Most have tubercules, which are frequently spiky or hairy. Many colors are cryptic, with countershading or disruptive colouring to limit detection, although some are more vibrant. Some people have urticating hairs. When agitated, a few species have been seen to make clicking sounds with their larval mandibles. Actias luna and Polyphemus moth are two examples (Antheraea polyphemus). The clicks might be aposematic warning signs to a regurgitation defense.
