A NOTE ON THE DISPERSAL OF COLEOPTERA. 165 



For it seems only probable that these survivors formed but an 

 attenuated minority of the original emigrants, vast numbers must have 

 perished in the open sea and no doubt during that week the fish of the 

 Dogger enjoyed unusual fare. It was on the beach south of the town 

 where I observed these ill-starred mariners in greatest abundance — more 

 precise data as to their numbers here may be of interest. Within 

 one lineal foot, approximately, measured off on the shore, I counted 

 eighty-three specimens of G. polyi/oni between the foot of the cliffs 

 and the sea, and on one fiat stone with a superficial area of some two 

 square feet sat no less than one hundred and thirty beetles belonging 

 to about seventeen different species — in fact every large stone on the 

 shore was covered by them there ; they sat drying themselves in the 

 hot sunshine rapidly back into life and activity, and it was noticeable 

 that their disastrous experiences in the deep seem to have stimulated 

 rather tban damped their amatory fires. 



As regards the species represented, all were such as readily occur 

 on cultivated land, clover fields, and the like. (jr. polij(jnni, already 

 mentioned, was easily first as regards numbers, then came three com- 

 mon species of Sitones — S'. jiavescens, S. lineatus, S. crinitus, four or 

 five Aiiimia, such as A. pisi, A. loti, etc., then, very abundantly, Mantura 

 rustira : the remainder was made up in much smaller proportions by such 

 common TachypoH and Tachini as T. ni/ipes and T. In/pnoreae, A}ihodius 

 ater, Euniaiuis wimNff;."!, sundry common liJiinonclii and Ceuthon/ij/)ichi 

 and rarely Hi/pera polyijoni, in all, perhaps, not more than twenty 

 species, although, among miles of beetles such as there were here, no 

 doubt other and rarer species sporadically occurred. 



I have thought the incident worthy of record at some length, 

 because it appeared to illustrate in singularly dramatic fashion a 

 factor which must operate very largely in the dispersal and consequent 

 extension of range of coleoptera. Both it and the Llyn dur Arddu 

 record as well as observations made on Coleoptera casually occurring 

 on the summit of Ben Nevis (see Annah of Scottish Natural History, 

 January, 1895), reported by Kev. A. Thornley, F.L.S., etc., seem to 

 impl}' that a hot sunny day after cold and wet weather acts on 

 beetle-life as an extraordinary stimulus to active, extensive, but 

 apparently undirected, flight. 



The operative agent of dispersal is undoubtedly the wind, not miora- 

 tory instinct, in the proper sense of the term, on the part of the beetles, 

 and, although at first it may appear difficult to understand how such 

 a habit (of undirected flight) could have arisen, of which the result 

 might be to the majority of the participants in it, irretrievable disaster, 

 still it must be considered that such results are very largely local, 

 partial, and due to the accident of insularity, and that, in larger 

 continental areas, such a tendency might be conducive rather to the 

 welfare of the species by the extension of its range than inimical by the 

 destruction of a large part of its members. 



Moreover, we may, perhaps, I venture to think, obtain some idea of 

 how largely this habit of impulsive flight may imply the difference 

 between species which are " common " everywhere and those which, 

 for no physiological reason which we can detect, are generally rare or 

 abundant only quite locally — for the former, their environment ceasing 

 to be adapted to their needs, are in this way involuntarily moved on to 

 "fresh woods and pastures new," while the latter, owing to their 



