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Butterflies in the Garden

by Keith Hansen, Smith County Extension Horticulture

Have you seen many butterflies lately? Much of the summer may go by with only an occasional sighting of a butterfly. Then, suddenly, they seem to be everywhere. Other years butterflies are plentiful. Weather and the environment play a big role in the annual abundance or scarcity of many species of butterflies. In some cases, human activity also plays an important role.

Take for instance the monarch butterfly. This marvel of nature makes an annual migration each fall to a very small mountainous area in central Mexico, where up to 100 million monarchs overwinter in the protected areas of oyamel fir forests. However, logging in the area has greatly reduced these overwintering areas, causing great concern regarding the long-term survival of these flying gems. Several of the main overwintering areas have been designated as sanctuaries, but they are in isolated locations and it is difficult to prevent unauthorized logging.

An amazing fact is that most of the monarchs joining the migration each fall are 3-4 generations removed from those that made the journey the previous year. How they make their way back to the very same locations, thousands of miles away, where their “great, great grandmothers” overwintered is one of the miraculous mysteries of nature.

The monarch breeding areas in eastern North America are recolonized by two generations of monarchs; the overwintering butterflies that move north from Mexico in the spring and their offspring. The latter reach maturity and begin flying north in late April, reaching the northern limits of milkweeds, their larval host plant, by mid-June.

Migratory monarchs that survive the winter in Mexico are 8-9 months of age and may be the longest lived of all butterflies. In contrast, reproductive monarchs breeding during the summer months only live 2-5 weeks.

Many more details about the amazing monarch butterfly can be found at the web site http://monarchwatch.org – an organization dedicated to research, conservation, and providing the public with information about the biology of monarch butterflies, their spectacular migration, and how to use monarchs to further science education in primary and secondary schools.

monarch watch signOne of the programs sponsored by Monarch Watch is the Monarch Waystation, which encourages people to create monarch habitats at home and at school. The IDEA Garden in the Tyler Rose Garden has been designated as a Monarch Waystation. Requirements include having a diversity of flowering plants attractive to not only monarchs, but all kinds of butterflies. Planting milkweed species is a key component of a Monarch Waystation.

monarch on tropical milkweedMilkweed is a critical food plant for monarch larval or caterpillar stage, which feed almost exclusively on several different species of milkweed (Asclepias). While milkweed sounds weedy, they are actually very well-behaved and attractive plants for any flower garden. They are also a magnet for many other insects. We often see them loaded with aphids - tiny, sap-sucking insects that crowd along the stem and on tender, new growth. Since the milkweed doesn’t seem to be adversely affected by the aphids, we suggest leaving them alone, because many beneficial insects come to dine on these fat little insects. Thus, the milkweed also helps build up the population of the good bugs in your garden.

Attracting Butterflies. If you want to enjoy a wide variety of beautiful adult butterflies flitting about your yard, you must provide various types of plants for both adults and the larval stages. A diverse perennial flower garden, mixed with annuals, perennials, vegetables, flowering shrubs and vines, will attract an assortment of butterflies. Caterpillars usually need different food plants than the adults, so having a variety of plants increases the diversity of butterflies attracted to your yard since adults are drawn to larval food plants on which to lay their eggs.

Larvae feed on the leaves and flowers of shrubs, trees, annual and perennials, while the adults require the nectar of flowers and other sweet things such as decaying fruit and wet wood. Of course, don’t spray your flower garden with insecticides or you will kill the very caterpillars you are trying to attract.

eastern blackswallowtail on bronze fennelI like growing bronze fennel in my garden. It is very attractive with its dark bronzy, finely cut foliage. Fennel is a favorite food of the Eastern Black Swallowtail. Just this week the caterpillars have finally appeared, so many in fact that I’m concerned they will not have enough to eat to reach maturity.

Another wonderful plant in my garden that hosts a wide variety of adult butterflies is summer phlox (Phlox panniculata). It has bright, magenta/pink blooms that last for several weeks, and butterflies (and hummingbirds) flock to this easy sun-loving perennial.

A few other larval plant suggestions for attracting butterflies:Giant Swallowtail Larvae on citrus

  • Passionflower (Passiflora) – larval host plant for Gulf Fritillary (beware – the vine suckers)
  • Dutchman’s Pipe (Aristolochia) – larval host plant for Pipevine Swallowtail
  • Pawpaw (Asimina) – larval host plant for Zebra Swallowtail
  • Parsley, fennel, dill – larval host plant for Eastern Black Swallowtail
  • Citrus and Hercules' Club (Zanthozylum clava-herculis) - larval host plants for Giant Swallowtail (see photo on right)

Some good nectar plants: Salvia, Lantana, Butterfly Bush, Almond Verbena, Zinnias, Tithonia, Abelia, Gomphrena, Sedum, Turk’s Cap, Azaleas, Ixora, Penta, Phlox.

For a very extensive listing of adult and larval host plants, visit the North American Butterfly Association web site, and in particular, the North Central Texas plant list - http://www.naba.org/ftp/nctx.pdf