Some Caterpillar Foods

     There are many kinds of caterpillars, both of moths and butterflies, in eastern North America and they all feed on certain kinds of vegetation.  But some species consume the foliage of one or a few specific types of plants.  Those caterpillars are too well adapted to specific vegetation for food.  It's easier, I suppose, for female moths and butterflies to lay eggs on just a few kinds of plants, but overspecialization could lead to those insects' demise.  Those kinds of moths or butterflies could become extinct if their larval food plants do, and if those insects don't adapt to other types of foods.  
     Tent caterpillars are moth larvae that feed on wild cherry leaves during May.  They live in tents of webbing they make themselves and venture out, mostly at night, to feed.  By the end of May they pupate in the soil and emerge a few weeks later as small moths ready to reproduce.
     The green larvae of I O moths also consume cherry tree foliage during summer.  The adult moth of this species has a large, fake "eye" on each hind wing that makes those wings together look like the alarming face of an owl, which scares off would-be predators.   
     Rosy maple moth caterpillars, as their name implies, eat the leaves of red and silver maple trees.  The lovely moth of this species has pink on its wings.
     Locust under wing moths have gray front wings that camouflage them on tree bark where they rest during the day.  Their back wings, however, are black and red, which could startle birds when those wings are suddenly exposed.  The caterpillars of this moth eat only the foliage of black locust trees.  
     The larvae of milkweed tiger moths, which are furry for their protection against predation, eat only milkweed leaves.  These caterpillars are attractive, however, with their many tufts of burnt-orange, black and white hairs all over. 
     Hickory-horned devils, the caterpillars of regal moths, are frightening to people as well as to birds and other critters.  They are about six inches long, mostly green and have several long, poison-filled spines of different colors on their bodies that would give any predator a nasty mouthful.  This larvae only eats the foliage of hickory and walnut trees. 
     Caterpillars of hackberry and snout butterflies consume only the leaves of hackberry trees.  Snout butterflies have what looks like a tiny nose in the front of their faces.
     Female red admiral butterflies lay their eggs mostly on stinging nettle plants early in May.  Stinging nettle is also called burn hazel, which stings or burns our skin a bit when we touch it, yet it is a food of those caterpillars.  I wonder how they do it. 
     By the end of May the mostly gray red admiral larvae ate many of the leaves of each plant and are ready to pupate in the ground.  A few weeks later they emerge as beautiful, red and chocolate butterflies ready to breed.   
     The tiny pearl crescent larvae feed exclusively on aster leaves and stems.  The small butterflies of this species have a one inch wing spread and are mostly a lovely orange and brown on their wings.  Pearly crescents are one of the last butterflies to be seen in October, still feeding on nectar in aster blossoms. 
     The swallowtail family of butterflies is noted for the larvae of each species eating only one or two kinds of plants.  Zebra swallowtail caterpillars, for example, consume only the foliage of paw paw trees.  The range of zebra swallowtails is naturally restricted to the range of paw paws.
     Larvae of spicebush swallowtails eat only spicebush and sassafras foliage.  These caterpillars have a couple other interesting things about them.  They roll up the leaf they are eating with silk they make themselves so they can hide in it while they ingest it.  These mostly green caterpillars also have a fake eye on each side of the front part of their bodies that make them look like a snake or some other more fearsome creature.  Those fake eyes are so good that when I look deep into one of them, I get the eerie feeling the eye is looking back at me, even when I know the eye is a fraud.
     Black swallowtail larvae eat parsley, carrot and related foliage.  One can have these caterpillars in their yard simply by planting parsley.  They are pretty with green, yellow and black lines over the top of the body from front to back.
     Last, but not least, are monarch larvae.  They only eat leaves from members of the milkweed family.  Plant milkweeds if you want them in your yard.  Monarch caterpillars are attractive, with black, white and yellow stripes from flank to flank over the tops of their bodies. 
     But monarch butterfly migrations are the most intriguing part of their life cycle.  Adult monarchs leave certain forests on mountains in Mexico where they wintered early in March and push north.  Somewhere in the United States those monarchs breed, lay eggs and die.  The next generation continues north, breeds and dies.  But the fourth generation of monarch caterpillars of that same year pupate in September and do not mate or lay eggs.  They migrate southwest to those same forests on the same mountains in Mexico their great grandparents left that spring.  How do those butterflies know the way?  And how do they know they arrived in the right forests when they were never there before?  No one knows.  It is one of those great miracles of life on Earth.  And all that from lowly caterpillars eating milkweed leaves.
     Caterpillars are lovely, interesting creatures that feed on specific plants.  Perhaps their eating only certain kinds of vegetation lessens competition among them for food.  But it is dangerous to have only one or two means of support.