A tegmen designates the modified leathery front wing on an insect particularly in the orders

Order (biology)

In scientific classification used in biology, the order is# a taxonomic rank used in the classification of organisms. Other well-known ranks are life, domain, kingdom, phylum, class, family, genus, and species, with order fitting in between class and family...

 Dermaptera (earwigs), Orthoptera

Orthoptera

Orthoptera is an order of insects with paurometabolous or incomplete metamorphosis, including the grasshoppers, crickets and locusts.Many insects in this order produce sound by rubbing their wings against each other or their legs, the wings or legs containing rows of corrugated bumps...

 (grasshopper

Grasshopper

The grasshopper is an insect of the suborder Caelifera in the order Orthoptera. To distinguish it from bush crickets or katydids, it is sometimes referred to as the short-horned grasshopper...

s, cricket

Cricket (insect)

Crickets, family Gryllidae , are insects somewhat related to grasshoppers, and more closely related to katydids or bush crickets . They have somewhat flattened bodies and long antennae. There are about 900 species of crickets...

s and similar families), Mantodea (praying mantis), Phasmatodea

Phasmatodea

The Phasmatodea are an order of insects, whose members are variously known as stick insects , walking sticks or stick-bugs , phasmids, ghost insects and leaf insects...

 (stick and leaf insects) and Blattodea (cockroach

Cockroach

Cockroaches are insects of the order Blattaria or Blattodea, of which about 30 species out of 4,500 total are associated with human habitations...

es).

The nature of tegmina

The term tegmen refers to a miscellaneous and arbitrary group of organs in various orders of insects; they certainly are homologous in the sense that they all are derived from insect forewings, but in other senses they are analogous; for example, the evolutionary development of the short elytra of the Dermaptera certainly shared none of the history of the development of tegmina in the Orthoptera, say. Also, in some other insects fore- and hindwings differ both in texture and their role in flight, but are not universally regarded as tegmina. For example, the hemelytra

Elytron

An elytron is a modified, hardened forewing of certain insect orders, notably beetles and a few of the true bugs ; in most true bugs, the forewings are instead called hemelytra, as only the basal half is thickened while the apex is membranous...

 of some Hemiptera

Hemiptera

Hemiptera is an order of insects most often known as the true bugs , comprising around 50,000–80,000 species of cicadas, aphids, planthoppers, leafhoppers, shield bugs, and others...

 have been called tegmina by some authorities, but not by most modern authors.

Entomologists do not customarily refer to the fore wing of a beetle as a tegmen; strictly speaking, the term for beetles' fore wings is elytra

Elytron

An elytron is a modified, hardened forewing of certain insect orders, notably beetles and a few of the true bugs ; in most true bugs, the forewings are instead called hemelytra, as only the basal half is thickened while the apex is membranous...

.

The function of tegmina

Probably the major role of tegmina in general is that of protecting the hind wings when folded. In many insects they also are important in camouflage and in displays, especially defensive display, where the tegmina are drab, but cover aposematic

Aposematism

Aposematism , perhaps most commonly known in the context of warning colouration, describes a family of antipredator adaptations where a warning signal is associated with the unprofitability of a prey item to potential predators...

 displays that that are startling when suddenly uncovered. Sometimes, as in some mantids, the tegmina crossed over the back are not striking, but when suddenly raised, act as a threatening display resembling a pair of eyes.

Tegmina do not play a major active, flapping role in flying, though they are aerodynamically significant in insects such as migratory locusts that fly vigorously for long distances. This is probably the main justification for distinguishing between say, the fore wings of cockroaches, which are called tegmina, and the fore wings of some Neuroptera, which though stiffer than the rear wings, are flapped in flight.

Tegmina and sound

Tegmina, generally being stiffer than the rear wings, are used as sound boards by many species of insects, especially Orthoptera; in many locusts they make a crackling noise in flight, and in many crickets, tree crickets, and even mole crickets, the tegmina have undergone marked anatomical adaptations, often asymmetric, for sound production.