April 1S91.J 



PSTCHE. 



67 



Halobates. The insect, of winch Dr. Ldon 

 had only a single specimen, is 4 mm. long. 

 Its mouth "is constructed exactly like that of 

 the Hemiptera," it has typical hemipteran 

 antennae, a pair of prominent compound 

 eyes, three stemmata, and the head is not 

 freely attached to the thorax. The wings, of 

 which only the mesothoracic pair is present, 

 appear to be hyaline, with a venation which by 

 no stretch of the imagination can be regarded 

 as dipteran. The legs are hairy and adap- 

 ted to swimming; there are three tarsal 

 joints, the last of which terminates in a sin- 

 gle claw. When we come to look for dipte- 

 ran characters the only one that can be found 

 is the lack of metathoracic wings; as if this 

 character were sufficient to elevate a hemip- 

 ter to the rank of a dipter! Has Dr. Leon 

 ever heard of the two-winged male Coccidae, 

 which no tyro in entomology would think of 

 placing among the Diptera? The stemmata 

 furnish Dr. Leon with another reason for re- 

 garding his insect as allied to the Diptera, 

 because, forsooth, the Hydrocorisa have no 

 stemmata! We are informed that at the 

 very beginning of his examination of this 

 insect, Dr.. L^on saw that he was not dealing 

 with a Halobates but with a form which re- 

 sembles a dipter more than a hemipter. He 

 further states that Dr. Arnold Lang, to whom 

 he communicated his observations was of the 

 same opinion. We cannot believe that so 

 eminent a phylogenist as Dr. Lang could 

 have examined the specimen. The insect is 

 not a hemidipter but a genuine hemipter 

 albeit with only one pair of wings. It will 

 hardly be necessary to study its ontogeny 

 for the sake of ascertaining that it does not 

 hatch as a maggot and does not pass through 

 a quiescent pupa stage. W. M. Wheeler. 



Protection by conspicuous colors. — 

 The following passages in Lord Walsing- 

 ham's last presidential address to the Ento- 

 mological society of London are sugges- 

 tive : — 



•My attention was lately drawn to a pas- 

 sage in Herbert Spencer's 'Essay on the 



Morals of Trade.' He writes : — 'As when 

 tasting different foods or wines the palate is 

 disabled by something strongly flavoured 

 from appreciating the more delicate flavour 

 of another thing afterwards taken, so with the 

 other organs of sense, a temporary disability 

 follows an excessive stimulation. This holds 

 not only with the eyes in judging of colours, 

 but also with the fingers in judging of tex- 

 tures. ' " 



"Here, I think, we have an explanation of 

 the principle on which protection is undoubt- 

 edly afforded to certain insects by the pos- 

 session of bright colouring on such parts of 

 their wings or bodies as can be instantly cov- 

 ered and concealed at will. It is an un- 

 doubted fact, and one which must have been 

 observed by nearly all collectors of insects 

 abroad, and perhaps also in our own country, 

 that it is more easy to follow with the eye 

 the rapid movements of a more conspicuous 

 insect soberly and uniformly coloured than 

 those of an insect capable of changing in an 

 instant the appearance it presents. The eye, 

 having once fixed itself upon an object of a 

 certain form and colour, conveys to the mind 

 a corresponding impression, and if that im- 

 pression is suddenly found to be unreliable 

 the instruction which the mind conveys to 

 the eye becomes also unreliable, and the ra- 

 pidity with which the impression and conse- 

 quent instruction can be changed will not 

 always compete successfully with the rapid 

 transformation effected by the insect in its 

 efforts to escape. . . . 



"If this protective effect of the partial and 

 intermittent display of brilliant colouring is 

 so obvious in relation to the human eye, 

 must it not be at least equally so in relation 

 to the eyes of its more natural enemies, such 

 as birds, and have we not here indicated a 

 new and distinct line of investigation as re- 

 gards the use and advantage of brilliant 

 colours in many cases which cannot be ac- 

 counted for by the theory that they are de- 

 veloped for the purpose of warning, or 

 through their aesthetic relation to court- 

 ship ? " 



