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Silkmoth caterpillar is showstopper
by Tammy Zellner, Goliad State Park Ranger
Nov 20, 2013 | 47 views | 0 0 comments | 13 13 recommendations | email to a friend | print
This photo displays the life cycle stages of the calleta silkmoth, which can grow to as large as a human hand.
This photo displays the life cycle stages of the calleta silkmoth, which can grow to as large as a human hand.
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GOLIAD – When people think of wildlife, they often focus on megafauna like deer, bobcats and such. But when you slow down and look closely, you’ll start to notice the little creatures - like the fun and funky caterpillars.

Bright colors, interesting textures and unique host plants make caterpillars interesting and their remarkable life cycles make them even more so. They can be fuzzy, spiny or smooth or fat, skinny or bumpy. They can also look like just about anything, including tiny snakes and bird droppings. One thing is for certain - you’re never quite sure what they’ll turn into.

One of my favorites is the calleta silkmoth (eupackardia calleta), because the caterpillar resembles a Pixar character. It is bright lime green with varying orange, yellow and blue spots with a black spikey apex.

The caterpillar emerges from eggs laid in rows or clusters on various host plants including ceniza (leucophyllum frutescens), ash (fraxinus), Mexican jumping bean (sapium biloculare) and ocotillo (fouquieria splendens). I’ve even seen them happily chowing down on yellow bells or esperanza (tecoma stans)

The tiny caterpillar emerges from the egg, but with a voracious appetite it quickly outgrows its skin (exoskeleton). As the caterpillar grows, it goes through several stages, shedding its skin each time.

Each stage is referred to as an “instar.” By the time the calleta silkmoth caterpillar reaches the fifth instar, it is as large as your thumb.

Throughout each stage, or instar, the caterpillar bulks up on purple sage leaves or other host plants before eventually attaining its final stage as a caterpillar - the cocoon. The caterpillar spins a silk peduncle, attaches it to a stem and then creates a solid, opaque cocoon.

On the plant, the cocoon looks like a little brown paper sack. Once snug inside, the caterpillar begins its transformation. However, conditions must be just right before the moth will emerge. If conditions are not favorable, it may spend up to two years in the cocoon.

The calleta silkmoth has a beautifully tragic life cycle. In South Texas, it has two seasons, or broods, which occur from September through November and then again from March through April. The adult moths work their way out of their cocoons in the evening.

They look pretty bedraggled at first, with damp, crinkled wings and a fattened body. They find a spot to dry out and stretch out their wings and, when morning comes, they begin to transmit signals to attract a mate.

By the end of the same day, the female lays her eggs in clumps on host plants.

The adult moths lack a digestive system. They don’t eat and this graceful beauty has a sole purpose - starting a new generation as quickly as possible.

The adult lifespan of the calleta silkmoth is not gauged in months or weeks, but in hours. It is therefore critical that they find a mate and breed in the few short hours before they expire.

The adult calleta silkmoth is a true beauty. Its exotic markings include red patches on the collar and rear of the thorax.

Wing patterns are marked with burgundy, blue and shades of brown. Triangular white spots on the wings range from large to almost absent.

The most striking attribute of the calleta silkmoth is its size. With a wingspan of nearly five inches, it is almost as large as one’s hand.
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