By Mary Hoff naturalists Y oung Wild ▼ Woollya n d S o m e t i m e s These creep along, munching on leaves. chubbyinsects I a bright spring day, perfect for playing catch. But you and your t’s friend are still a little out of practice from the long winter, so you end up in the bushes, looking for an overthrown ball. What is that!? The brightly colored, stumpy-legged creature looks like nothing you’ve ever seen. Welcome to the wild—and sometimes woolly—world of Minnesota caterpillars. A caterpillar is a wormlike insect called a larva. When fully grown, a caterpillar will turn into a moth or a butterfly. Caterpillars come in many shapes, sizes, and colors. Some are smooth, fat, and green. Others are hairy, prickly, and brown. Some have spines that look like horns. Others have spots that look like eyes. Some caterpillars live in trees. Others spend their time on flowers. Minnesota is home to at least 800 species of moths and about 140 butterfly species. That means almost 1,000 different species of caterpillars Colorful fleshy knobs, known as are creeping, crawling, and munching their way through summer days. tubercles, grow on the body of This story introduces a few you might find in your yard or at the park. BILL JOHNSON the cecropia moth caterpillar. Black spikes on the tubercles warn potential 44 Minnesota Conservation Volunteer May-June 2016 predators to look for an easier meal. 45 Like every insect, a caterpillar has six true legs. It also Some are smooth Fun has pairs of stumpy parts called prolegs to help grip and spiracles Fact White-lined sphinx moth anatomy (breathing holes) open crawl. Prolegs have muscles but no hard parts. to take in oxygen and close Lepidoptera THORAX ABDOMEN to keep out water 3 segments Moths and butterflies are insects that be- frogs, spiders, bears, or other predators. horn long to a group called Lepidoptera. Look Sometimes wasps, flies, or other insects lay HEAD for butterflies during the day when they eggs inside a caterpillar. When those eggs are sipping nectar from blossoms. Most hatch, the young insects, or parasitoids, eat moths are active after dark, but many the caterpillar from the inside. stemmata 4 pairs of stumpy anal prolegs abdominal prolegs moths are day fliers. You can see hungry If a caterpillar survives long enough, it mandibles 3 pairs of true (thoracic) legs Final instar can be moth and butterfly caterpillars eating eventually stops eating and gets ready for spinneret up to 3 inches long almost anytime in summer. its next stage of life. It changes into a pupa, Even though different kinds, or species, a new form with hardened, shell-like skin. 3rd instar of caterpillars look very different from By its jaw, a caterpillar has a little nozzle head anatomy each other, they all share some common called a spinneret. It can force a unique head capsule body parts. See if you can find the parts liquid out of its spinneret. The liquid clypeus on the next caterpillar you spy. hardens into silk. Some moth caterpillars (front of face) use silk to make a cocoon. Like a sleeping stemmata 2nd instar A Wonderful Life. (eyes) A caterpillar’s story bag, the cocoon covers the pupal shell. A starts when a female moth or butterfly lays butterfly pupa, usually called a chrysalis, at- a tiny egg, most likely on a leaf or twig. After taches itself to a silk pad by hooks on its rear. 1st instar a week or two, a little larva hatches from the During its pupal stage, the caterpillar antenna egg. A caterpillar has one job: Eat! Chomp- goes through a change called metamor- ing leaf after leaf with its jawlike mandibles, phosis. Inside the shell, the caterpillar’s mandibles (jaws) spinneret Egg on leaf it grows astoundingly quickly. In a week or muscles and other tissues break down, dis- two, some caterpillars can gain hundreds of solving into a soupy mix. From this mushy times their hatching weight. caterpillar, tiny “seeds” of adult moth or Some are hairy Forest tent caterpillar The different stages of a caterpillar’s life butterfly parts, calledimaginal discs, build (Malacosoma disstria) are called instars. A newly hatched caterpil- an adult insect with wings. lar is a first instar larva. When it grows too After two weeks, or sometimes longer, This camouflaged-looper caterpillar big for its skin, the caterpillar splits and sheds an adult moth or butterfly emerges from glues flower petal bits to its back with silk from its spinneret. its skin. Then it’s a second instar larva. Most the pupal shell. It stretches its wings and caterpillars go through four or five instars. flies off to begin its most important job: It’s an eat-and-be-eaten world for cat- Reproduce! The caterpillar-turned-flying- erpillars. Before they get a chance to grow insect mates and lays eggs to make the Some decorate themselves LITWAK TAINA BY ILLUSTRATION up, most become juicy tidbits for birds, next generation of caterpillars. The caterpillar of the wavy-lined emerald moth is called a camouflaged-looper caterpillar 2 pairs (Synchlora aerata). abdominal prolegs May-June 2016 47 Moth Caterpillars PHOTOS BY BILL JOHNSON PHOTOS IsabellaTiger Moth Pyrrharctia isabella ForestTentCaterpillar Moth Also known as a woolly bear, this is one place. A chemical in its hemolymph—the Malacosoma disstria of Minnesota’s best-known caterpillars. insect equivalent of blood—helps keep it Walking through the woods in May, you oak, and other trees, this caterpillar can Fuzzy and black with a fat orange-brown from freezing to death. might see a tree that seems like it forgot grow to be 2 inches long. band around the middle, it grows to about When spring comes, the woolly bear to grow some of its leaves. Looking a little Sometimes mistakenly called “army- 2 inches long. Some people think that the warms up and starts eating again. After closer, you might notice that its twigs are worms,” which is a different species, these wider a woolly bear’s brown band, the a few days to weeks, it spins a cocoon. In- swarming with hairy black-and-blue cat- caterpillars often gather in “conventions” milder the winter will be. In reality, the side, it changes to a pupa and then finally erpillars. Chomping on leaves, they have of 100 or more on a silk mat attached to band gets wider as the woolly bear grows. an adult moth. The moth emerges in almost stripped the tree bare. branches. They make the mat by laying People often spy this caterpillar cross- midsummer. It mates, lays eggs, and dies Forest tent caterpillars hatch in early down several layers of silk. ing a road, sidewalk, or bike path in the within a few days. The caterpillars that spring from egg bundles wrapped About mid-June, the caterpillars stop fall as it searches for shelter from the cold. hatch from those eggs might have time to around branches. At first, a larva is about eating. They make silk cocoons. A week or A woolly bear spends winter curled into a become moths that same summer. Their as long as a grain of rice. Voraciously gob- two later, furry brown moths emerge. They ball in a pile of dead leaves or another cozy offspring then overwinter. bling tender new leaves of aspen, birch, lay eggs, and the cycle begins again. 48 Minnesota Conservation Volunteer May-June 2016 49 Moth Caterpillars WHITE-LINED SPHINX MOTH BY BILL JOHNSON SPHINX MOTH WHITE-LINED CECROPIA MOTH BY BILL JOHNSON White-LinedSphinx Moth COURTESY OF ROBERT DANA Hyles lineata Also known as a hornworm, this mainly grape and tomato plants, the hornworm green-and-black caterpillar has a horn- can grow to be more than 3 inches long. CecropiaMoth like spike sticking up from its back near When full-grown, it burrows into the soil COURTESY OF ROBERT DANA its rear end. No one knows for sure how and becomes a pupa. Hyalophora cecropia the spike helps the caterpillar. What do An adult sphinx moth emerges from One of Minnesota’s biggest caterpil- this caterpillar on a tree or shrub dur- you think? the pupal shell after a couple of weeks. lars (along with the big poplar sphinx, ing summer. White-lined sphinx moths migrate into With its long tongue, it drinks nectar Pachysphinx occidentalis), this creepy Because the cecropia moth does not Minnesota from the southern United from flowers, just as hummingbirds do. crawler can stretch up to 5 inches long have mouthparts or digestive organs, it States in spring. They mate and lay eggs. When finished drinking, the moth coils when fully grown. When it first hatch- must survive on fat stored up during its Tiny caterpillars hatch from eggs in July. its tongue up neatly below its face. es, it has black skin covered with bris- days as a caterpillar. Nibbling leaves of primrose, fireweed, White-lined sphinx moths cannot sur- tles. Later it turns yellow, then green This species goes through one genera- apple and elm trees, and sometimes vive in Minnesota during winter. with brightly colored knobs. Look for tion each year. 50 Minnesota Conservation Volunteer May-June 2016 51 Moth Caterpillars Butterfly Caterpillars MONARCH BUTTERFLY BY BILL JOHNSON MONARCH BUTTERFLY PHOTOS BY BILL JOHNSON PHOTOS Wavy-LinedEmerald Moth Synchlora aerata Do you like to dress up? The caterpillar of with its true legs and lifting its body into the wavy-lined emerald moth does. Called the shape of a loop. This motion brings the a camouflaged-looper, it feeds on flowers rearmost prolegs up next to the true legs.