INDIRECT BENEFITS DERIVED FROM INSECTS. 295 



insect of this kind that Aristolochia Sip/to never forms 

 fruit in this country. 



Equally important is the agency of insects in fructifying 

 the plants of the Linnean classes Monoecia, Dioecia and 

 Polygamia, in which the stamens are in one blossom and 

 the pistil in another. In exploring these for honey and 

 pollen, which last is the food of several insects besides 

 bees a , it becomes involved in the hair, with which in many 

 cases their bodies seem provided for this express purpose, 

 and is conveyed to the germen requiring its fertilizing in- 

 fluence. Sprengel supposes that with this view some plants 

 have particular insects appropriated to them, as to the 

 dioecious nettle Catheretes Urticce^ to the toad-flax Cathc- 

 retes gravidus, both minute beetles, &c. Whether the ope- 

 rations of Cynips Psenes be of that advantage in fertilizing 

 the fig, which the cultivators of that fruit in the East have 

 long supposed, is doubted by Hasselquist and Olivier b , 

 both competent observers, who have been on the spot. 

 Our own gardeners, however, will admit their obligations 

 to bees in setting their cucumbers and melons, to which 

 they find the necessity of themselves conveying pollen from 

 a male flower, when the early season of the year precludes 

 the assistance of insects. Sprengel asserts, that apparent- 

 ly with a view to prevent hybrid mixtures, insects which 

 derive their honey or pollen from different plants indis- 

 criminately, will during a whole day confine their visits to 

 that species on which they first fixed in the morning, pro- 

 vided there be a sufficient supply of it c ; and the same ob-' 



a I have frequently observed Dermestes flavcscens, Ent, Brit, eat 

 both the petals and stamens of Stellaria Holosteum ; and Mordellce will 

 open the anthers with the securiform joints of their palpi to get at the 

 pollen. b Hasselquist's Travels, 253. Latr. Hist. Nat , xiii. 204. 



r Willd. Grundriss, '352, 



