INSECTS. 333 



winged and the female wingless. It is notorious that bees 

 express certain emotions, as of anger, by the tone of their 

 humming; and according to H. Miiller (p. 80) the males 

 of some species make a peculiar singing noise while pursu- 

 ing the females. 



Cokoptera (Beetles). Many beetles are colored so as to 

 resemble the surfaces which they habitually frequent, and 

 they thus escape detection by their enemies. Other species, 

 for instance diamond-beetles, are ornamented with splendid 

 colors, which are often arranged in stripes, spots, crosses 

 and other elegant patterns. Such colors can hardly serve 

 directly as a protection except in the case of certain flower- 

 feeding species; but they may serve as a warning or means 

 of recognition on the same principle as the phosphorescence 

 of the glow-worm. As with beetles the colors of the two 

 sexes are generally alike, we have no evidence that they 

 have been gained through sexual selection; but this is at 

 least possible, for they may have been developed in one sex 

 and then transferred to the other; and this view is even in 

 some degree probable in those groups which possess other 

 well-marked secondary sexual characters. Blind beetles, 

 which cannot of course behold each other's beauty, never, 

 as I hear from Mr. Waterhouse, Jr,, exhibit bright colors, 

 though they often have polished coats; but the explanation 

 of their obscurity may be that they generally inhabit caves 

 and other obscure stations. 



Some Longicorns, especially certain Prionidse, offer an 

 exception to the rule that the sexes of beetles do not differ 

 in color. Most of these insects are large and splendidly 

 colored. The males in the genus Pyrodes,* which I saw 



* Pyrodes pulcherrimus, in which the sexes differ conspicuously ? 

 has been described by Mr, Bates in "Transact. Ent. Soc.," 1869, p. 

 50. I will specify the few other cases in which I have heard of a 

 difference in color between the sexes of beetles. Kirby and Spence 

 ("Introduct. to Entomology," vol. iii, p. 301) mention a Cantharis, 

 Meloe, Rhagium, and the Leptura testacea ; the male of the latter 

 being testaceous, with a black thorax, and the female of a dull red 

 all over. These two latter beetles belong to the family of Longi- 

 corns. Messrs. R. Triinen and Waterhouse junior inform me of two 

 Lamellicorns, viz., a Peritrichia and Trichius, the male of the latter 

 being more obscurely colored than the female. In Tillus elongatus 

 the male is biack, and the female always, as it is believed, of a dark 

 blue color, with a red thorax. The male, also, of Orsodacna atra, as 

 I hear from Mr. Walsh, is black, the female (the so called 0. rvficol- 

 lis) having a rufous thorax. 



