Essays
Moseying: Exploring the Natural World
Overwintering grasshoppers may mean summer population explosion
April 2, 2008
Spring has gotten folks thinking about gardening (and by the way, I hope you are coming to the plant sale on Saturday, April 5th, at 9 a.m. at the Sibley Nature Center.) Gardening has its perils, however, and it may be that this year will be a banner year for grasshoppers. Folks in town usually do not have to worry much about grasshoppers, but we exurbanites with property in the rural countryside might just be in for some trouble this year.
The Llano Estacado Chapter of the Texas Master Naturalists has been exploring West Texas habitats this spring. On our most recent field trip (to Borden County’s “breaks habitat”) we found a half-dozen species of grasshoppers already active. (Look for upcoming photoessays from that field trip on our website’s “habitats” section.) Many were adults, which means they managed to survive our mild winter. With the plentiful rain last year, the grasshoppers that hatched last year were able to survive and lay eggs, so the conditions are right for a population explosion of grasshoppers. With it being dry, the grasshoppers may start migrating, looking for greener pastures, which will include home landscapes, even in town.
That scares me. In 1987 the grasshoppers were so plentiful that they stripped the leaves of every plant. The mulberry trees even had the bark stripped off the younger branches, as well as all of their leaves. Other species of trees had their leaves gobbled up in just one day. Even sotol, that tough yucca-like plant with saw-toothed edged leaves, was badly eaten. Resinous annual wildflowers like sawtooth daisy became bare sticks. It was terrifying – we could do nothing!
Most of the grasshoppers during that plague were of the same species that stopped a Midland Cubs game in 1973. Those grasshoppers were migrating, pushed south by a cold front that generated huge thunderstorms further north on the Llano Estacado. In 1987, however, the species had proliferated locally because of the incredible rains of 1986. Every egg laid hatched (and grasshoppers lay up to 100 eggs at a time). The birds and other predators of grasshoppers could not keep up with the billions of babies.
That year’s plague was a harsh reminder of the great grasshopper plagues that lasted until the 1880s and prevented the Great Plains from becoming farmland in the first decade of settlement. The early day plagues featured a migratory species that became extinct because the settlers in the west tilled the soil along the rivers of the region where the species laid its eggs. The grasshoppers of the 1987 plague were a close cousin to the extinct species. At Sibley we did some “quadrat studies,” tossing hula-hoops randomly and then counting the grasshoppers within the hoops. We averaged 10 grasshoppers per hoop! We estimated 50,000 grasshoppers per acre (and over two million in our 49 acres).
If a person went walking along the trail, grasshoppers would land on one’s shirt, pants, hair, and even on the face. It was creepy and scary! Grasshopper poop and their “tobacco” drool would stain a walker’s clothes. If a person left a shirt outside, the grasshoppers would gnaw holes in the cloth. We even heard reports of roads becoming slick from the bodies of roadkilled grasshoppers.
The grasshopper population explosion became the focus of our summer camp that year. This summer the Sibley Nature Center will be holding bug camp for 4th through 6th graders. Instructor Michael Nickell will be taken the students out on the trail to help him start a professionally-done insect collection for us. Every species of insect on the trail will be the target, but if the summer does indeed turn out to be a grasshopper year, he might continue some of the studies we began in 1987. Call him at 684-6827 to be put on a registration list.
During the 1987 summer camp we put together a list (from books at UTPB) of possible grasshopper species for West Texas. Over 120 species might be found in our region. We found 35 species that year. One of the most amazing discoveries we made was that the painted grasshopper has “lekking behavior” where the males gather in groups and sing and perform to attract the females.
Some grasshoppers are terricoles, feeding on the ground, and are usually gray, brown, and mottled. These often have wings with bands of color, crepitate (make noise when they fly), fly rapidly, and land facing what scare them. Others are graminicoles, feeding in grass and are usually green or yellow with longitudinal striping. These are often slantfaced, long and angular. They freeze when a threat approaches, and do not fly very well. Other species are small and spend most of their life in one species of plant. Others do not fly at all.
A dozen or more species have variable colors – sometimes green, sometimes brown. Some species are sexually dimorphic – the males are one color, and the females a different color. One genera (with a possible 20 species in the region) can only be identified by habitat, song, period of adulthood, display routines, or genitalia! Grasshoppers are paurometabolic -- once born, a grasshopper is always a grasshopper (no metamorphosis). Grasshoppers are polyphagous as well -- they eat anything, including paint. Grasshopper spit is acidic.
Under a hand lens grasshoppers appear to be mechanical contraptions, aliens with a malevolent expression. Up to thirty milligrams of vegetation is eaten daily. Seven grasshoppers per square yard is enough to alter the amount of forage, the growth of plants, and the dynamics of seed production. A serious infestation can change habitat and lead to soil erosion. It is not only man that alters the landscape, for many creatures disturb ecosystems with regularity.
Grasshoppers are important food supplies for many birds and other predators that appreciate a grasshopper meal (especially the grasshopper mouse, that fierce little predator who howls at the moon.) I hope grasshoppers do not eat my garden again, not this year! See you at the plant sale on Saturday!