170 INDIRECT BENEFITS DERIVED FROM INSECTS. 



return ; several creep in, and, uneasy at their confinement, are constantly 

 moving to and fro, and so deposit the pollen upon the stigma ; but when 

 the work entrusted to them is completed, and impregnation has taken 

 place, the hair which prevented their escape shrinks, and adheres closely 

 to the sides of the flower, and these little go-betweens of Flora at length 

 leave their prison. 1 Sir James Smith supposes that it is for want of some 

 insect of this kind that Aristolochia sipho never forms fruit in this country. 



Equally important is the agency of insects in fructifying the plants of the 

 Linnean classes Moiwecia, Dlceda, 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 2 , it becomes 

 involved in the hairwith which in many cases their bodies seem provided 

 for this express purpose, and is conveyed to the germen requiring its ferti- 

 lising influence. Sprengel supposes that with this view some plants have 

 particular insects appropriated to them ; as to the dioecious nettle Cathe- 

 retes urticce, to the toad-flax Catheretes gravidus, both minute beetles, &c. 

 Whether the operations of Cynips psencs be of that advantage in fertilising 

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

 is doubted by Hasselquist and Olivier 3 , both competent observers, who 

 have been on the spot. 4 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, apparently with a view to prevent hybrid mixtures, insects 

 which derive their honey or pollen from different plants indiscriminately 

 will, during a whole day, confine their visits to that species on which they 

 first fixed in the morning, provided there be a sufficient supply of it 5 ; and 

 the same observation was long since made with respect to" bees by our 

 countryman Dobbs. 6 



Thus we see that the flowers which we vainly think are 



" born to blush unseen, 



And waste their fragrance on the desert air," 



though unvisited by the lord of the creation, who boasts that they were 

 made for him, have nevertheless myriads of insect visitants and admirers, 

 which, though they pilfer their sweets, contribute to their fertility. 



I am, &c. 



1 Grundriss der Krauterkunde, 353. A writer, however, in the Annual Medical 

 Review (ii. 400.) doubts the accuracy of this fact, on the ground that he could never 

 find C. pennicornis, though A., clematitis has produced fruit two years at Brompton. 

 Meigen (Dipt. i. 100. e.) places this amongst his doubtful Cecidomyice. Fabricius 

 considers it as a Chironomus. 



2 I have frequently observed Dermestes flavescens, Ent. Brit. (Byturus} 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. 



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



4 For a full account of the various opinions on this disputed point, see an interest- 

 ing article by Mr. Westwood in Trans. Ent. Soc. Land. ii. 214 224. 



6 Willd. Grundriss, 352. 6 phil Trans, xlvi. 536. 



