TASTE IN INSECTS. 39 



as in a sort of bug (Pentatoma), and sometimes 

 into the stomach itself, as in the bee flies (Syrphi, 

 Bombylii). It is remarkable that the latter insects, 

 from feeding exclusively on the nectar of flowers, do 

 not require a supply of saliva to moisten their food in 

 the first instance, though it appears to be indispen- 

 sable to digestion ; while in bugs (Reduvius, Pen- 

 tatoma), which feed on vegetable and animal juices, 

 one pipe opens into the sucker (haustellum), to en- 

 able the animal to soften, if necessary, the skin it has 

 to pierce through, and another into the stomach or 

 gullet to aid digestion. In the common flies (Muscce)^ 

 again, and the gad-fly (Tabanus), both pipes open 

 into the sucker, and we have already seen the in- 

 genious use which is made of this when the insects 

 feed on dry sugar. In the water- scorpion (Nepa ci- 

 nerea*), there are no fewer than six of these vessels, 

 though it is rare that there are more than two in other 

 insects. It is worthy of remark, that the exterior 

 double pair in the Nepa, is found, when highly mag- 

 nified, to consist of little globules resembling a bunch 

 of currants ; and a similar structure has also been 

 detected in one of the bee flies (Syrphus arcuatus), 

 precisely like what we have above described, as oc- 

 curring in our own salivary fountains. 



In the case of drinking thin fluids, like water, 

 saliva is not wanted ; and, it may be remarked, when 

 we drink cold water it actually astringes and shuts 

 up the openings of the salivary pipes : hence it is 

 that drinking does not quench thirst when the saliva 

 is rendered viscid and scanty by heat, by fatigue, 

 or by the use of stimulant food and liquor ; and 

 sometimes a draught of cold water, by carrying off 

 all the saliva from the mouth, and at the same time 

 astringing the orifices of the ducts, may actually 

 * Figured in Insect Transformations, page 121. 



K2 



