On a mid-November desert excursion, I encountered a most unusual insect. It’s not uncommon to observe grasshoppers, but this individual was distinctly different in several ways. Its length size and coloration was overshadowed by its behavior. The grasshopper appeared to be feeding on a piece of sun-bleached bone! And, it was relatively unresponsive and refused to take flight when I nudged it with a stick. It was Taeniopoda eques, commonly known as a horse lubber or Mexican general.
T. eques is native to the desert brush and grasslands of southern Arizona and New Mexico and west Texas, where it is predominantly black with yellow markings. Its southern range extends into central Mexico, where its yellow markings increase, particularly on the vestigial forewings. The antennae display orange and black bands. The hind wings of males are red and may be displayed when threatened.
The dramatic coloration of the horse lubber, called aposematic coloration, combined with a foul smelling/tasting foam emitted from the horse lubber’s spiracles, form a defense mechanism that warns off potential predators. The warning mechanisms are so successful the species doesn’t fear or need to flee from potential predators.
The predominance of black body coloration within the northern range of the species is advantageous in another way. It allows the horse lubber to thermoregulate and maintain its body temperature between 86 and 104 degrees Fahrenheit for much of the day. Individuals expose themselves to the sun or seek shade to maintain a body temperature range favoring metabolic development which allows for a shorter life cycle. This differs from grasshopper species with lighter body colorations.
Horse lubbers overwinter as pods of up to 50 eggs laid into the ground at the bases of shrubs and rocks. Females coat the pods with a substance which quickly dries to form a protective crust. The eggs hatch in synchrony during the rainy season. In dry years eggs will remain unhatched for another year. Upon hatching, horse lubber nymphs are red, but change to black within a matter of hours. They go through a succession of 5 molts before attaining adulthood in October. Hatchlings and molting individuals are most susceptible to predation. T. eques nymphs are gregarious and may be seen marching in mass much like an invading army. Adults become solitary but may be seen feeding together on favored foods.
Like other grasshoppers, the horse lubber feeds on a wide range of plants and has been reported to feed on dung. My observing an adult female chewing on a dried piece of bone is out of the ordinary for grasshoppers. In researching T. eques, I discovered reports of the species not only cannibalizing its own, but feeding on the carrion of mammals. Necrophagy appears to be more common among adult female horse lubbers than males and is believed to be a means of supplementing the nutrients necessary for oocyte development.
For additional information on the horse lubber, conduct a web search using the scientific name Taeniopoda eques.