BRACHYPTEKOUS EARWIGS. 



199 



Described from a single female specimen received from Dr. 

 L. 0. Howard, mounted in balsam, and labelled : " 923. Perth, 

 W. Austr. G. Compere." 



Habitat. — West Australia (Perth). 



Type.— Type, No. 13,704, United States National Museum, 

 Washington, D.C. ; a single female in balsam. 



BRACHYPTEKOUS EARWIGS. 

 By Malcolm Burr, D.Sc, M.A., F.E.S., F.L.S., F.Z.S., &c. 



In the earwigs, as in the true Orthoptera, and also in the 

 Hemiptera, we find that brachypterism in normally macropterous 

 species, and vice versa, is a frequent form of dimorphism. Thus, 

 in Marava grandis, Dubr., Labia tetragona, Bor., L. unidentata, 

 P. Beauv., Echinosoma parviditm, Dohrn, Allostethus indicum, 

 Hagenb., and many other species, macropterous specimens are 

 as frequent as those with shortened wings. 



The absence of the protruding squamae, or chitinised portion 

 of the wings, from beneath the elytra materially alters the 

 superficial appearance of the creature. When the wings are 

 abbreviated, the elytra are often, but not always, correspondingly 

 reduced to a lesser, but distinct, degree, in which case they are 

 apically truncate. The disturbance also frequently afi'ects the pro- 

 notum : thus in Marava grandis, Dubr., in the macropterous forms, 

 the pronotum is decidedly broadened posteriorly, the hinder mar- 

 gin gently convex, and hinder angles distinctly rounded; whereas 

 in bracbypterous specimens the pronotum is not trapezoidal, 

 but square, the sides being parallel, and posterior margin trun- 

 cate. The superfical appearance of the creature is so altered by 

 these reductions that two dimorphic forms are not infrequently 

 described as distinct species ; thus Forjicula miranda, Borm., and 

 Nesogaster acideatus, 13orm., are respectively the macropterous 

 and bracbypterous forms of one and the same insect. 



We find the same phenomenon in the polymorphic and 

 ubiquitous Labidura riparia, Pall., of which some brachyi)terous 

 forms, with reduced elytra and squared pronotum, have been 

 placed in a special genus, Demogorgun, Kirby, which, needless to 

 add, cannot stand. 



But brachypterism has not yet been recorded in the common 

 earwig, Forjicula auricidaria, L. There is, however, known in 

 Italy a rather rare species F. silana, Targ. (=-P. targionii Br.), 

 which only differs from the common species in the broader, more 

 truly rectangular pronotum, truncate and somewhat shortened 

 elytra, and aborted wings ; it is, in fact, nothing more or less 



