Clare Island Survey — Orthopteru. 31 3 



•of Cambridge. Mr. Brindley is studying the variation of mainland and 

 island Earwigs, in continuation of the observations which he published in 

 1892 in collaboration with Professor W. Bateson, on the forceps of male 

 Earwigs collected on the Fame Islands off the coast of Northumberland. Of 

 about 1000 Fame Island specimens, 583 were males, and these showed a 

 marked dimorphism with regard to the length of the forceps, the majority of 

 the specimens falling into two groups averaging respectively 3 - 5 mm. and 

 7 mm. in the forceps-length. It seems that on the mainland of Great Britain 

 : high " males — as those with long forceps are called — are relatively scarce. 

 Mr. Brindley in a recent letter has kindly informed me that 40 per cent, of 

 the Earwigs collected on Clare Island were males, and that among these there 

 Avere no strikingly " high " specimens, and only a " slight suggestion of 

 dimorphism." The Earwigs of Clare Island, therefore, show far less 

 " insularity " in character than those of the Fame Islands on the east coast 

 ■of Great Britain. Among the specimens which I have examined, a male from 

 Louisburgh has 7 mm. forceps, while two Clare Island males have forceps 

 only 4 - 5 long. 



The Common Earwig is one of the most abundant and widespread insects 

 in the British Islands, and has an immense foreign range — Europe, North 

 Africa, Madeira, western Asia, and North America. 



DISTRIBUTIONAL NOTES. 



With the exception of . Mecostethus grossus, which was not found on Clare 

 Island, and of the House Cricket, the species of Orthoptera listed above are 

 among the commonest of Irish insects. The family of the Long-horned 

 ■Grasshoppers (Phasgonuridae), which is but scantily represented in the. Irish 

 fauna, has no representative in the above list, no specimen of the group 

 having been found in the district. The genus Gomphocerus, belonging, like 

 Stenobothrus and Mecostethus, to the Acridiidae, which occurs in the south 

 and south-west of Ireland, is also absent, so far as our present knowledge 

 goes, from Clare Island and its neighbourhood. 



So far as the Orthopterous fauna is concerned, we may conclude that 

 Clare Island was peopled from the mainland, and the general distribution of 

 five of the species found on the island does not suggest an immigration prior to 

 the Glacial Period. None of the Grasshoppers nor the Earwig can be 

 declared incapable of having reached the island, even since its separation 

 from Co. Mayo ; and Gryllus domesticus, a messmate of Man, may have been 

 introduced artificially. The discontinuous range of Mecostethus grossus, on the 

 other hand, suggests considerable antiquity, and despite its general northern 



