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| The white patches on the black body of this Cottonwood Borer are actually areas of pubescence or short, dense hairs. |
Colorful things typically catch our eye, but the patterns formed by black and white can often be the most striking. In nature, these patterns can be achieved through contrasting chemical pigments or structural elements such as scales or pubescence (or hairs). While somewhat rare but not uncommon, these distinct black and white combinations are particularly striking in three native beetles, the Cottonwood Borer (Plectrodera scalator), the Texas Click Beetle (Alaus lusciosus), and the Texas Ironclad Beetle (Zopherus nodulosus haldemani).
The Cottonwood Borer is an unmistakeable, robust, elongate beetle with a shiny black body up to 1.6 inches long, and irregular, contrasting markings of white pubescence. It has long, black antennae and prominent spines on the side of the pronotum, or the plate-like structure that covers all or part of the thorax. As an adult it is most active in summer, feeding on leaf petioles (stalks) of cottonwoods, willows, and sycamores, and is often found near the base of these trees. Its' larvae bore into the base of the tree, living under the bark, and require 2 to 3 years to reach maturity.
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| Cottonwood Borer, from above |
Present in Central, South, and East Texas, the Texas Click Beetle, up to 2 inches long, has distinctive, large, round black eyespots its pronotum, usually encircled in white. White markings made of scales on its black body are clumped and patchy rather than evenly dispersed, and can sometimes look faintly yellowish. Its common name comes from the fact that they possess an unusual clicking mechanism, whereby a spine on the prosternum (the underside of the thorax) can be snapped into a corresponding notch that produces a violent click that bounces the beetle into the air. It is mainly used to avoid predation but can be useful when it needs to right itself. Its species name means ‘dim-sighted’, and it can be found under loose tree bark.
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| Texas Click Beetle |
The Texas Ironclad Beetle, a nocturnal beetle up to 1.5 inches long, has a distinctively round pronotum and raised black bumps or knobs on a white body. It has a phenomenally strong exoskeleton, very thick and hard, in part due to its interlocking elytra or wing covers. As such, it cannot fly but will play dead for long periods of time if touched or disturbed. Also called Haldeman’s or Southwestern Ironclad Beetle, the Texas Ironclad Beetle is endemic to East and Central Texas, and it is active as early as March and into late October. It has been associated with dead or dying pecan, oak, and elm trees, and has been found feeding on lichen. Each part of its scientific name has relevance; zopher comes from Greek and means ‘dark' or 'dusky’, nodulus comes from Latin and means ‘little knot' or 'knob’, and haldemani refers to Horace Haldeman (1820-1883), one of the first to concentrate on collecting insects in Texas.
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| Texas Ironclad Beetle |
The next time you see a beetle that is black and white all over, take a closer look at these fascinating creatures. You just might find them to be as interesting as their more colorful cousins!
