''Anisomorpha buprestoides'', the southern two-striped walkingstick, devil rider, or musk mare, is a

stick insect The Phasmatodea (also known as Phasmida, Phasmatoptera or Spectra) are an order of insects whose members are variously known as stick insects, stick-bugs, walking sticks, stick animals, or bug sticks. They are also occasionally referred to as ...

(order Phasmatodea: otherwise known as "phasmids" or walkingsticks) which occurs throughout the

southeastern United States The Southeastern United States, also referred to as the American Southeast or simply the Southeast, is a geographical region of the United States. It is located broadly on the eastern portion of the southern United States and the southern por ...

. ''Anisomorpha buprestoides'' is a large, stout (for a stick insect) brown phasmid with three conspicuous longitudinal black stripes. Females average in length; males are smaller and more slender, averaging .

Defense

This species, and another in the same genus ('' Anisomorpha ferruginea'', whose range is more west and north, but may overlap with ''A. buprestoides'') is particularly well known for its very potent chemical defense spray which it deploys from a pair of glands which open at the front of its thorax. The "Devil rider" name for this insect likely comes from this defense, as well as the fact that they are most frequently encountered in the late summer and fall when they are active adults at a time when almost all of them are found in mating pairs, with the smaller male riding on the back of the larger female. The chemical defense of this species was first studied by

Thomas Eisner Thomas Eisner (June 25, 1929 – March 25, 2011) was a German-American entomologist and ecologist, known as the "father of chemical ecology." He was a Jacob Gould Schurman Professor of Chemical Ecology at Cornell University, and Director of the ...

and Jerrold Meinwald (two scientists at Cornell University who helped found the field of chemical ecology). They found the chemical defense spray of this species was found at the time to contain predominantly a cyclopentanyl monoterpene dialdehyde compound which they called " anisomorphal".

Color morphs

This insect comes in three regionally specific color forms: a "brown form" which is predominantly dark brown with light brown stripes, a "white form" that is jet black with bright white stripes and an "orange form". The white and orange forms are only known to occur in relatively small specific areas of Florida. All three color forms each have unique behaviors of aggregation, diurnal activity cycles and egg laying which conform to the ecological conditions in which they are found. They have also been determined to produce somewhat unusual chemical defense cocktails (at least as adults) – with the white and orange forms producing primarily "anisomorphal" and the brown form producing either anisomorphal or peruphasmal (a

stereoisomer In stereochemistry, stereoisomerism, or spatial isomerism, is a form of isomerism in which molecules have the same molecular formula and sequence of bonded atoms (constitution), but differ in the three-dimensional orientations of their atoms in ...

of anisomorphal), depending on the population sampled.

Nymphs A nymph ( grc, νύμφη, nýmphē, el, script=Latn, nímfi, label=Modern Greek; , ) in ancient Greek folklore is a minor female nature deity. Different from Greek goddesses, nymphs are generally regarded as personifications of nature, are typ ...

of the brown form have been shown to produce predominantly varying mixtures of anisomorphal and

dolichodial Dolichodial is a natural chemical compound with two aldehyde groups, which belongs to the group of iridoid Iridoids are a type of monoterpenoids in the general form of cyclopentanopyran, found in a wide variety of plants and some animals. They ...

(another stereoisomer of anisomorphal) with peruphasmal remaining a trace component until they are sexually mature. Additionally, the chemical defense of this species, as well as that of other phasmids, has been found to contain glucose, which may be involved in the later stages of its

biosynthetic pathway Metabolism (, from el, μεταβολή ''metabolē'', "change") is the set of life-sustaining chemical reactions in organisms. The three main functions of metabolism are: the conversion of the energy in food to energy available to run cell ...

similar to pathways shown for some

leaf beetle The insects of the beetle family Chrysomelidae are commonly known as leaf beetles, and include over 37,000 (and probably at least 50,000) species in more than 2,500 genera, making up one of the largest and most commonly encountered of all beetle ...

s (family Chrysomelidae). The white color form was featured on the cover of the March issue of ''

Annals of the Entomological Society of America Annals ( la, annāles, from , "year") are a concise historical record in which events are arranged chronologically, year by year, although the term is also used loosely for any historical record. Scope The nature of the distinction between anna ...

'', 2009. The orange color form was also featured on the cover of the issues of the ''

Journal of Natural Products The ''Journal of Natural Products'' is a monthly peer-reviewed scientific journal covering all aspects of research on the chemistry and/or biochemistry of naturally occurring compounds. It is co-published by the American Society of Pharmacognosy ...

'' from July through December, 2011.

References

{{Taxonbar, from=Q149362 Phasmatodea Insects of North America Fauna of the Southeastern United States Insects described in 1813