992 



INSECTS AND ARACHNLDA 



great distance beyond the other parts of the mouth ; but when at 

 rest it is closely packed up and concealed between the maxilhe. ' The 

 manner,' says Mr. Newport, ' in which the honey is obtained when 

 the organ is plunged into it at the bottom of a flower is by " lapping." 

 or a constant succession of short and quick extensions and contrac- 

 tions of the organ, which occasion the fluid te accumulate upon it 

 and to ascend along its upper surface, until it reaches the orifice of 

 the tube formed by the approximation of the maxilla? above, and of 

 the labial palpi and this part of the ligula below.' 



By the plan of conformation just described we are led to that 

 which prevails among the Lepidoptera, or butterfly tribe, which, 

 being pre-eminently adapted for suction, is termed the haustellate 

 mouth. In these insects the labium and mandibles are reduced to 

 three minute triangular plates ; whilst the maxilla' are immensely 

 elongated, and are united together along the median line to form 



the haustellum, or 

 true ' proboscis,' 

 which contains a 

 tube formed by the 

 j unction of the two 

 grooves that are 

 channelled out 

 along their mutu- 

 ally applied sur- 

 faces, and which 

 serves to pump 

 up the juices of 

 deep cup-shaped 

 flowers, into which 

 the size of their 

 wings prevents 

 these insects from 

 entering. The 



length of this haustellum varies greatly : thus in such Lepidoptera as 

 take no food in their perfect state it is a very insignificant organ ; in 

 some of the white hawk-moths, which hover over blossoms without 

 alighting, it is nearly two inches in length, and in most butterflies and 

 moths it is about as long as the body itself; in A-ni-])/to)i-y.r, one of the 

 Sphinyidce, it is more than nine inches long, or about three times the 

 length of the body. This haustellum, which, when not in use. is 

 coiled up in a spiral beneath the mouth, is an extremely beautiful 

 microscopic object, owing to the peculiar banded arrangement it ex- 

 hibits (fig. 740), which is probably due to the disposition of its muscles. 

 In many instances the two halves may be seen to be locked together 

 by a set of hooked teeth, which are inserted into little depressions 

 between the teeth of the opposite side. Each half, moreover, mav 

 lie ascertained to contain a trachea or air-tube, and it is probable, 

 from the observations of Mr. Newport, that the sucking up of the 

 juices of a flower through the proboscis (which is accomplished with 

 greal rapidity) is effected by the agency of the respiratory apparatus. 

 The proboscis of many butterflies is furnished, for some distance from 



FIG. 740. Haustellum (proboscis) of Vanessa. 



