Essays

Wild On The Prairie: Invertebrates

Invasion of the flitterbys -- billions of snout butterflies from the Brasada
August 2, 2006

Photos by Richard Galle; click on thumbnail to view full-sized image

During the last week of July, a butterfly invasion occurred. Dozens of people called the Sibley Nature Center to ask a variety of questions: “Are they a pest? What do they eat? Where did they come from? Are they moths or butterflies? Just what is the dang deal?”

A similar invasion of the same butterfly, the snout, occurred in 1983. Exponential population explosions of arthropods are memorable, but irregular. Some Midlanders may remember the Midland Cubs baseball game interrupted by migrating grasshoppers in 1973. Others may remember the mesquite twig girdler invasion of 1996 that left millions of the beetles dead at the doors of brightly lit business and schools over the span of a few days.

The snouts are here to lay eggs on hackberry trees, and sip the nectar of flowers. Hackberry trees are rarely found in any ornamental landscape, although every draw and rocky arroyo anywhere close to Midland has scattered groves of hackberries. This is an occasion to marvel – to be moved with awe by the fecundity that nature can produce. “God sent them to make us stop and look,” one caller told me last Friday. And I am glad that so many people did look! “Butterflies make people smile,” according to Sybil Eberhart of the Midland Naturalists.

The snouts came from the Brasada. J. Frank Dobie fans know that term for the “brush country triangle” from San Antonio to Brownsville to Uvalde. Spiny hackberry is native there, and is the preferred larval food plant for snouts. (They will munch on our netleaf hackberry trees and the sugar hackberry to the east, but prefer the spiny.) On the Midland Naturalist Butterfly Count on July 8th, only 3 Snouts were found during 150+ man-hours of observation.

Exponential irruptions occur because a certain set of conditions occurs. Snouts usually are plagued with parasitoids (small flies and wasps that lay eggs on a snout larvae and whose larvae eat the snout caterpillar while it is eating hackberry.) Due to long-term drought conditions in the Brasada, the parasitoid numbers were very low, so when the first generation of snouts born this year were munching away on the new leaves of spring, nothing significantly limited their numbers.

That first generation laid eggs in June, when good soaking rains caused another big crop of new spiny hackberry leaves. The parasitoids still had not recovered, so the second generation defoliated the spiny hackberry in the Brasada. To cause such a complete defoliation, observers calculated that a half million caterpillars per acre were present. Frass (caterpillar poop) dropping to the ground sounded like rain, I bet!

The second generation had to leave the Brasada to be able to complete their job – to mate and lay eggs. The butterflies spread over most of Texas, but the Gulf winds from the southeast brought us significant numbers. Nobody here had to stop and clean their windshields as people had to in Uvalde and Rock Springs and Kerrville, but still – I counted over 100 in a one mile stretch of old Lamesa Road just south of I-20 while driving home at 45 mph.

I am a goofy old coot – I went out and played with the snouts. Or, I should say, they played with me, while I tried to take a photograph of them. I had watered the dark blue Ceratostigma and the bright red Bouvardia the night before. When I walked between them hundreds of snouts parted like little fluttering waves of froth arcing sequentially, and then immediately returned to the garden path to puddle. A number of butterfly species land on wet soil in big numbers to get a drink, but the snouts were constantly moving and I never succeeded in getting a decent photograph. Sibley staffer Richard Galle had better luck – he even photographed two mating!

I am not sure how many folks have a kidneywood in their home landscape. The Sibley Nature Center has one it its Jean and Aubrey Reid Native Plant Garden. It is not a showy plant, for it is just another one of those “desert scrubs” that look dead if you don’t take a good look. It has tiny dark green compound leaves and small spikes of white blossoms. As the name would indicate, the genus has been medicinally for centuries. If you put a piece of its wood in water at night it will begin to fluoresce (glow in the dark.)

The kidneywood was planted at the Sibley Nature Center by the Llano Estacado chapter of the Native Plant Society of Texas over a decade ago. The group disbanded a couple of years ago. When asked why, one of their officers told me, “Native and drought adapted plants are now available at most nurseries – and our plant sale grew too big for us to handle.” The Master Gardeners still hold the plant sales, and this spring’s sale at the Horseshoe still sold out within an hour despite having twice as many plants as the native plant society ever had. I hope kidneywood was one of the species offered!

The three local network television stations all came to the Sibley Nature Center to do a story on the snouts. When Sam Conn of CBS7 called me Thursday evening to set up an appointment for a photographer to visit, I knew I wanted Midland’s favorite butterfly enthusiast JoAnn Merritt to be featured in the story. For years JoAnn gave a wonderful program on butterflies to local schools and civic groups. She and her husband Don are what I call “village relatives.” Don has made or fixed things– from building a Bird Observation Tower for my mom to inventing a special lawn mower to maintain a trail for the Midland Naturalists at the I-20 Wetlands. JoAnn’s bright and joyful spirit is a wonder in itself – she communicates spiritual joy in the wonders of nature to everyone.

The CBS7 photographer set his camera up and started it up, then walked to the shrub and shook it 300 to 400 snouts swirled in a glittering halo around it. “Oh, how grand! Yeah! What fun! Do it again!” JoAnn laughed.

On August 26th The Southern Llano Estacado Chapter of the Texas Master Naturalists will hold the first of 8 daylong classes (once a month.) All classes will be on a Saturday. In addition to the curriculum developed by the Texas Parks and Wildlife Department covering basic ecological concepts and a review of statewide ecology, students will be introduced to the flora and fauna of West Texas. Instructors include employees of the Texas Parks and Wildlife Department and local experts. The cost is $75 or $125 for a couple. Field trips to ranches in the region are included. Call 684-6827 and ask for Burr for more details, or to reserve a spot in the class. Thank you, Sammy Hunnicutt of Big Spring, for spearheading the committee that met the requirements of the state organization so the class can be offered! Space is becoming limited, so call soon, if want to join in on the fun.