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Honey mesquite – what do moths have to do with it?

-- National Moth Week July 23 to 31


Published July 16, 2022, in the McAllen Monitor


Story and photos by Anita Westervelt, Texas Master Naturalist


Nothing says Texas like a breezy grove of honey mesquite trees (Prosopis glandulosa). Relatively quick-growing, mesquites furnish shade and wildlife habitat where other trees will not grow.


Honey Mesquite Grove. (Photo by Anita Westervelt)

Bird lovers appreciate the mesquite’s excellent nesting and roosting attributes; leaves, bark and flowers attract insects, which in turn attract insect-eating birds. Quail, doves, roadrunners and other birds eat mesquite bean pods, as do rabbits, rodents, coyotes, raccoons, skunks and other critters. Seeds, leaves, flowers, bark, twigs and foliage provide food for animals and insects alike; the flowers attract native bees, wasps and butterflies. The little mesquite cicada, generally the first cicada to emerge in summer, is associated with mesquite.


If all that’s not enough for one species to offer, mesquite trees also are larval food plants for local butterflies, like the long-tailed skipper, marine, ceraunus and Reakirt’s blues and gray hairstreak. In some years, the flowing branches of leaflets house hundreds of American snout butterflies, providing cover and nectar during their sporadic mass migrations.


But this is about moths and annual National Moth Week, July 23 to 31. In addition to all its other valuable wildlife qualities, mesquite trees feed the caterpillars of interesting, colorful and good-sized local moths – as a matter of fact, the largest moth north of Mexico, the good-luck black witch moth, with its seven-inch wingspan, uses honey mesquite as a host plant; the caterpillars eat the bean pods. The adult moths are nectarous and can be attracted to soft, overripe fruit, if you want to be hospitable.


Black Witch Moth on a moth sheet. (Photo by Anita Westervelt)

Heiligbrodt’s mesquite moth caterpillars use the leaves of honey mesquite for food. The moth is light gray-olive-drab colored with a wingspan just over three inches. The forewings have scalloped brown median lines on the upper side; their hindwing coloring is red at the base. The adult moth does not feed.


Heiligbrodt's Mesquite Moth. (Photo by Anita Westervelt)

Two other distinctive moths that use mesquite trees for larval food are the brightly colored io moth and the indomitable graphic moth. The male io moth is bright yellow with black markings. When its three- and one-half-inch wingspan is spread, the hind wings show red markings and two huge black spots – a classic example of startle coloration to scare predators. The female forewings are brown.


Io Moth, male. (Photo by Anita Westervelt)


Male Io Moth on moth sheet. (Photo by Anita Westervelt)

Less showy, indomitable graphic moths look like a tapestry design in velvety brown and tan colors; great numbers of these moths are often attracted to lights at night. Their habitat range is the southern portion of the United States where mesquite trees are found.


Indomitable Graphic Moth. (Photo by Anita Westervelt)

Annual moth week is a global event, promoting appreciation of moths. This year, it is being celebrated in all 50 U.S. states and 90 countries. Moths play a vital role in the ecosystem. Female moths can lay hundreds of eggs during their life subsequently producing caterpillars that become food for other wildlife, such as other insects, spiders, frogs, toads, lizards, bats and birds. Moths themselves are a food source of much wildlife.


Setting up a moth-attracting activity at home makes for a unique summer project; for ideas, visit https://nationalmothweek.org/finding-moths-2/;alternately, check with local park and nature center personnel for scheduled mothing events.