1. A magic charm, talisman, or spell.
2. Magic power.
Based on a recent perusal of current literature and various internet sources, it appears that some information concerning the behavior, seasonality, alleged rarity, and color forms of Cicindela (Cicindelidia) hornii Schaupp warrant further discussion. Apparently, a great deal of this information and supposition is based upon brief incidental field collections - or lack of - and observations. For most collectors and students of tiger beetles, this species is a fortuitous hit-or-miss opportunity - a collateral species. As a result, it carries an exaggerated distinction as being a rare and highly coveted species.
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| Typical habitat of Cicindelidia hornii Schaupp Upper Sonoran Mesquite-Grassland Sulphur Springs Valley, Cochise County, Arizona |
The term rare is so commonly used (= misused) in entomology, that in fact, it has lost its connotation. Remember, when dealing with things biological - anything is possible. Consider that beetles, and insects in general, emerge and become active when a certain combination of physiological and environmental stimuli are reached (for example, moisture, temperature, humidity) indicative of phenotypic plasticity: any change in an organism’s characteristics in response to an environmental signal (Schlichting and Smith 2002:190).
In southwestern North America, moisture, in the form of either winter rain or summer monsoons, is an essential factor in this equation. Without this necessary moisture insects may delay their emergence for several months or years. My point being, there are prevailing factors that influence, or deter, fecundity (abundance), of an organism - despite the exhortations of frustrated collectors.
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| Another habitat photo of Cicindelidia hornii Schaupp Upper Sonoran Mesquite-Grassland Sulphur Springs Valley, Cochise County, Arizona |
In southeast Arizona, C. hornii emerges during the summer monsoon that typical begins in late June or early July. It is best described as an ephemeral species because it is active while the soil remains damp after rainfall. Once this moisture evaporates, it disappears along with several other sympatric species, such as Cicindela pulchra dorothea Rumpp (below, left). Cicindelidia hornii typically occurs in grassy pastures and roadsides where it will hide in the shade beneath grass clumps or other vegetation during morning to mid-day hours or seen running in open areas in search of prey.
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| Cicindela pulchra dorothea Rumpp |
Polymorphism is the occurrence of more than one color form, or morph, in the same population of a species. Of the various publications and websites that display images of C. hornii, usually only one or two color forms are illustrated. Based on specimens in my collection, iridescent metallic blue, blue-green head and pronota with purple elytra, blue-green to green, and black are represented. The latter melanistic form being the most commonly encountered. Although anecdotal, from my field observations, it appears that the more brilliantly colored individuals appear earlier in the season. Victor E. Shelford, in his treatise, Color and color-pattern mechanism of Tiger Beetles (1917), noted that tiger beetle coloration was influenced, in part, by climatic conditions.
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| Color variation of Cicindelidia hornii Schaupp: blue, bluegreen head & pronota with purple elytra, bluegreen-green, black. Sulphur Springs Valley, Cochise County, AZ |
Literature Cited
Schlichting, C. D., and H. Smith. 2002. Phenotypic plasticity: linking molecular mechanisms with evolutionary outcomes. Evolutionary Ecology 16:189–211
Shelford, V. E. 1917. Color and color-pattern mechanism of tiger beetles, with twenty-nine black and three colored plates.Volume Illinois Biological Monographs Vol.3: No. 4
Other Suggested Reading
Bertholf, J.K. 1979 (MS Thesis). Tiger Beetles of the genus Cicindela in Arizona (Coleoptera:Cicindelidae). 1983 (paperbound edition). Texas Tech University Special Publications, Texas Tech Press, Lubbock, Texas. #19:1-44. .pdf
Schultz, T.D., and N. F. Hadley. 1987. Structural Colors of Tiger Beetles and Their Role in Heat Transfer through the Integument. Physiological Zoology. 60 (6):737-745
© Delbert La Rue 2014. All Rights Reserved.
