1876. ] How Cockroaches and Earwigs fold their Wings. 521 
THE MODE IN WHICH COCKROACHES AND EARWIGS 
FOLD THEIR WINGS. 
BY SAMUEL H. SCUDDER. 
QEVERAL years ago, Dr. Henri de Saussure, of Geneva, pub- 
lished, under the title of Etudes sur l’Aile des Orthopteres,} 
some interesting observations on the structure of the wings of 
cockroaches. | He treated particularly of the folding of the 
wings in those groups of Blattarians where the wing is very 
ample and some contrivance necessary to insure its complete 
protection by the smaller wing-covers. The necessity of some 
peculiar arrangement in the winged genera of earwigs, where the 
extended wing is often ten times larger than the wing-covers 
(tegmina) is even more evident ; and to understand the nature 
of the structural modifications of a normal wing-type (which are 
here universal), it will be convenient and instructive to examine 
the cockroach’s wing on the basis of Saussure’s memoir, for in 
different genera of this group we have every stage of change 
from simple unreversed wings scarcely larger than the tegmina, 
to those of great size, curious complication, and unique mode of 
duplicature, 
In the hind wings of all Orthoptera, the anal area, or the area 
traversed by the nervules of the posterior part of the wing, is 
unusually ample; the branches of the anal vein are numerous 
and straight, and originate not far apart nor far from the base of 
the wing; when the wing is fully expanded they diverge like 
the rays of a fan; and like a fan they fold themselves against 
the sides of the body, the membrane of the wing folding along 
an edge midway between each pair of rays ; this admits of a 
large expansion of the anal field, and provided the wings are not 
quite so long as the tegmina, any breadth, folded close, may be 
= vered by this coriaceous appendage. This, however, would not 
= Necessarily be true, if the anterior part of the wing, provided 
with stiff interlacing veins, were itself as broad as the tegmina ; 
2 for then, if the front edges of the wings and tegmina were brought 
2 together, the entire folded anal area would extend beyond the 
_ *Pposite margin of the wing, quite unprotected ‘by the tegmina ; 
to obviate this, the line of separation between the anal area and 
© anterior part of the wing is itself an axis of duplicature, and 
e folded anal area always lies beneath the stiff anterior parts 
of the wing. 
1 Annales Se. Nat. [5] Zool. x. 161-200, plate 11. 
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