Got milkweed? A butterfly-loving friend of mine recently had that phrase printed on a bunch of bumper stickers. It’s a play on the popular “Got Milk?” campaign, but instead of promoting the calcium-rich beverage, it’s a witty reminder to feed baby butterflies—a step too many butterfly-loving gardeners overlook. Of course, baby butterflies aren’t smaller versions of the winged, nectar-sipping adults; they are plant-eating, wormlike larvae commonly known as caterpillars.
Get to know their good side.
Caterpillars have a bad reputation. As gardeners, we have a knee-jerk reaction to the sight of a caterpillar chewing holes in the leaves of our plants: we grab the pest spray. It is true that holey leaves can make for an ugly specimen plant, and it’s also true that some caterpillars are dangerous ecological pests (for instance, the invasive exotic gypsy moth caterpillar), but in most cases caterpillar damage is only superficial. Healthy garden plants do not die when a few caterpillars feed on them. Native plants are particularly well adapted to caterpillar use and won’t suffer any long-term damage. So let the little leaf-munchers be, and plan to enjoy the butterflies they will eventually turn into.
Remember that caterpillars attract birds.
Caterpillars are an important part of the food chain. Most birds rely heavily on them as a food source for their babies in the spring and summer and later as a critical calorie source for fall migration. Allowing caterpillars to go about their business will attract birds to your yard. Your feathered friends will do the dirty work of naturally removing excess larvae.
Create a butterfly nursery.
If you can put up with caterpillar damage and want to attract even more of them and their pretty parents, plant the host plants they need to survive. (See sidebar.) Most people think that planting lots of big, showy flowers will do the trick, but your goal is to give the butterflies a reason to lay their eggs in your yard. The most effective way to do this is with caterpillar host plants.
Providing a nectar source is important, too, but some butterflies don’t even feed as adults, and many don’t feed on flower nectar—they prefer sap, animal dung, or rotting fruit. Plus, many of the showiest garden plants are so changed from their wild forms that butterflies can’t access the nectar in them.
Butterflies also need dense vegetation to escape bad weather and to hide from predators. A cluster of shrubs, a wildflower patch, or even a brush pile will meet this need nicely. Some species enjoy sipping mineral-rich water from mud puddles, so consider leaving a muddy patch in the corner of the yard—or creating one by mixing compost and water in a birdbath—and you’ll make your garden even more attractive to butterflies.
LOVE THOSE LARVAE
Here’s a mini-guide to four common butterflies (and their caterpillars) you might encounter in your garden.
Butterfly: Large orange and black butterfly.
Caterpillar: Pale green with uneven stripes of black and white along entire body.
Host plant: Milkweed.
Butterfly: Large yellow and black butterfly; eastern female also has a dark color morph.
Caterpillar: Look like bird droppings when young. As they grow, they turn bright green or yellow with two “eye spots” and a yellow band on front end. Front end is fatter than back end.
Host plant: For the eastern species: tulip poplar, sweet bay magnolia, black cherry; for the western species: willow, cottonwood, aspen.
Butterfly: Medium-sized with rusty orange fading to purplish- brown with spots. Underside looks like tree bark with a white, comma-shaped marking.
Caterpillar: Mottled gray, black, and orange pattern with grayish- white back; bristly.
Host plant: Elm, hops, nettle.
Butterfly: Tiny blue-gray butterfly with small black or gray spots and markings on wings.
Caterpillar: Tiny, segmented, pale green with rust stripe down center of back.
Host plant: Dogwood, New Jersey tea shrub.
Photo: Bill Johnson