475 THE ARU ISLANDS. [chap, xxxii. 



with (;iiml»ers, yet I always managed to add sometbing daily 

 to my extensive collections, I one day met with a curious 

 example of fiiDure of instinct, whieb, by showing it to be 

 f alii hie, renders it veiy doubttul whether it in anytbino: more 

 than bereditary habit, dependent on delicate modifications 

 <if sensation. Some sailors cut down a irood-siiied tree, and, 

 as is always my practice. I visited it daily for some time in 

 search of insects. Among other beetles came swarms of 

 the Htt!e cylindrical wood-borers (Platjiius, Tesserocerus, 

 &c,), and commenced niakini^ holes in the bark. After a 

 day or two I was surprised to find bundi-eda of them 

 sticking in the holes they had bored, and on examination 

 discovered that the milky sap of the tree was of the nature 

 of gutta-percha, hardening rapidly on exposure to the air, 

 and glueing the Uttle animals in self-dug graves. The 

 babit of boring holes in trees in which to deposit their 

 cggg, was not accompanied by a sufficient instinctive 

 knowledge of which trees were suitatde, and which 

 destructive to them. If, as is very probable, these trees 

 have an attmctive odour to certain species of borers, it 

 might very likely lead to their becoming extinct ; while 

 other species, to whom the same odour was disagreeable, 

 and who therefore avoided the dangerous trees, woidd sur- 

 vive, and would be credited by us with an instinct, \vlierea9 

 they would really be guided by a simple sensation. 



Those curious" little beetles, the Brentbidie, w^ere very 

 abundant in Am. The females have a pointed rostrum, 

 with which tlioy bore deep boles in the bark of dead trees, 

 often bm-ying the rostrum up to the eyes, and in these 

 holes deposit their eggs. The males are larger, and have 

 the rostrum dilated at the eiid, and sometimes terminating 

 In a good-sized pair of Jaws. 1 once saw two males tight- 

 ing together ; each had a fore-leg laid across the neck of 

 the other, and the rostrum bent quite in an attitmle of 

 defiance, and looking most ridiculous. Another time, two 

 were fighting for a feuuile, who stood close by busy at her 

 boring. They pushed at each other with their rosti-a, and 

 clawed and thumped, apparently in the greatest mge, 

 although their coat^ of mail ra\ist have saved both from 

 injury. The small one, however, soon ran away, acknow- 

 ledging himself vanqmshed. In most Culeoptera the 



