The Saturniidae Moths’ Breathtaking Metamorphosis
A saturniidae moth caterpillar is what you’re looking at. The Saturniidae family includes the largest moth species, which have hair-like scaled bodies, lobed wings, reduced mouthparts, and small heads.
Adults have large, lobed wings, heavy bodies covered in hair-like scales, and smaller mouthparts. They lack a frenulum, but the hindwings overlap the forewings to create the illusion of a continuous wing surface.
Saturniids have translucent eyespots or “windows” on their wings that are sometimes brightly colored. Males have larger, broader antennae than females, but sexual dimorphism varies by species.
The majority of adults have wingspans ranging from 1-6 in (2.5-15 cm), but some tropical species, such as the Atlas moth (Attacus atlas), can have wingspans of up to 12 in (30 cm). Saturniidae, along with some Noctuidae, contains the largest Lepidoptera and some of the largest insects alive today.
The majority of saturniid species are found in wooded tropical or subtropical areas, with the greatest diversity in the New World tropics and Mexico, though they are found worldwide. There are approximately 12 described species in Europe, one of which, the emperor moth, is found in the British Isles, and 68 described species in North America, 42 of which are found north of Mexico and in Southern California.
Some saturniids are strictly univoltine, producing only one brood per year, whereas others are multivoltine, producing multiple broods per year. Spring and summer broods hatch in a matter of weeks, while autumn broods enter diapause and emerge the following spring. The pupae’s decision to hatch early or hibernate is not fully understood, but research suggests that day length during the fifth larval instar, as well as cooling temperatures, play a significant role.
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 individuals, or she can have a different number of broods in different years or parts of the range.
Spring and summer broods differ in some species; for example, the two Saturniinae species Actias luna (the Luna moth) and Callosamia securifera both have specific genes that may or may not be activated depending on environmental conditions.
We don’t know why the caterpillars have such a complicated appearance. This is how they appear after the transformation:
Saturniid caterpillars are stout, cylindrical, and large (50 to 100 mm in the final instar). Most have tubercules, which are frequently spiny or hairy. Many colors are cryptic, with countershading or disruptive coloration to reduce detection, but some are more colorful. Some people have urticating hairs.
When disturbed, a few species have been observed making clicking sounds with their larval mandibles. Luna moth (Actias luna) and Polyphemus moth are two examples (Antheraea polyphemus). The clicks could be aposematic warning signals to a regurgitation defense.
Most feed alone, but some feed in groups. When young, the Hemileucinae are gregarious and have stinging hairs,[2] with those of Lonomia containing a poison that can kill a human. Another well-known example is Arsenura armida, which is infamous for its large conspicuous masses during the day. Their coloring is not cryptic, but rather aposematism.
Other caterpillars in this size range are almost always Sphingidae, which are rarely hairy and have diagonal tries on their sides. On their hind end, many Sphingidae caterpillars have a single curved horn. Although these are not dangerous, large-haired caterpillars should only be handled by experts.
The majority of saturniid larvae feed on tree and shrub foliage. A few Hemileucinae species, including Automeris louisiana, A. patagonensis, and Hemileuca oliviae, feed on grasses. They moult at regular intervals, usually four to six times before pupation. A wandering stage occurs prior to pupation, and the caterpillar may change color, becoming more cryptic just before this stage.
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