If you’ve spent any time outside or in the garden lately, you've probably noticed that bees, butterflies, caterpillars and moths are out in full force this fall.

Insects are at work to insure the survival of their offspring, and fall is their last effort before going into winter dormancy.

October through December is an active season for butterflies and moths, which are mating and laying eggs that will lay dormant until temperatures are again favorable in spring. Other caterpillars are pupating in chrysalises and cocoons and overwintering to emerge as adults the following spring.

Butterflies and moths have four life stages — egg, larva, pupa and adult. Caterpillars are that second larva stage, when they spend most of their time eating leaves of various plants and growing.

Some of the most visible caterpillars this time of year are the monarch, Gulf fritillary, luna moth, giant swallowtail, sphinx moths and tent caterpillars.

Some caterpillars will devour anything, while others look for specific host plants, such as milkweed for monarch caterpillars, passionflower for Gulf fritillary and citrus fruit for giant swallowtails. 

In “Louisiana Native Pollinator Trees,” Chrissy Mogren notes which native trees provide nectar for different butterflies and which trees and shrubs provide food for caterpillar larvae. The publication is available at bit.ly/lslupollinatortrees.

Mogren’s list of butterfly and moth caterpillars and their host plants include:

  • Gray hairstreak butterflies feed on clover, cotton, mallow and pecan, while juniper hairstreaks prefer junipers and red cedars. Striped hairstreak caterpillars can be found on ironwoods and oak, while adult butterflies sip nectar from goldenrod, milkweed and viburnums such as the Louisiana Super Plant, Mrs. Schiller's Delight viburnum.
  • Hackberry emperor butterflies feed on several species of hackberry while mourning cloak, question mark and painted lady caterpillars all feed on American elm.
  • Willow trees are the host plant of the viceroy butterflies, which closely resemble the monarch, and eastern tiger swallowtails can be found on tulip poplar, ironwood and willow. Zebra swallowtails can be found only on pawpaw trees.
  • Spotted aptelodes host plants include ash, maple and oak. Red-spotted purple caterpillars can be found on oak, willow and ironwood trees. Banded tussock moth caterpillars and adult moths feed on ash, elm and hackberry.
  • Luna moth host trees include alder, beech, black walnut, butternut, hickory, pecan, persimmon, sweet gum, sumac and willow. Promethea moth host plants include black cherry and sweetbay magnolia.
  • Rosy maple moths are specific to red maple. Tulip tree silk moth prefers tulip poplar trees, and the bald cypress sphinx moth is host-specific to the bald cypress.
  • Hydrangea sphinx moth larval host plants include hydrangea and buttonbush, and pawpaw sphinx larval host plants include pawpaw, some species of holly and inkberry.
  • Rustic sphinx caterpillar host plants include fringe tree and Grancy greybeard while small-eyed sphinx feed on a variety of plants, including black cherry, chokecherry, sour cherry, serviceberry and basswood.
  • The spicebush swallowtail feed on spicebush, camphor tree, sassafras and red bay, and the woolly worm or banded woolly bear devours dandelion, aster, birch and goldenrod so prominent in the fall.

Luckily for curious observers, caterpillars are slow movers and easily spotted by their striking colors, spines or fuzzy hairs. Those with spines and hairs are typically stingers, but not always. Other caterpillars have evolved to mimic stingers to deter predators.

Hungry caterpillars can cause some damage to plants. But in most cases the damage can be tolerated with no real consequence to overall growth or quality. Defoliated plants will flush out new leaves quickly in most cases.


Email questions to gardennews@agcenter.lsu.edu.