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. 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 Monecia, Diecia, 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®, 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 ferti- 
lising influence. Sprengel supposes that with this view some plants have 
particular insects appropriated to them; as to the dicecious nettle Cathe- 
retes urtice, to the toad-flax Catheretes gravidus, both minute beetles, &c. 
Whether the operations of Cynips psenes 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®, 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, contine their visits to that species on which they 
first fixed in the morning, provided there be a sufficient supply of it®; and 
the same observation was long since made with respect to bees by our 
- countryman Dobbs. ® 
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. 
Tam, &c. 
1 Grundriss der Krtiuterhunde, 853. 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 Cecidomyie. Fabricius 
considers it as a Chironomus, 
2 Ihave frequently observed Dermestes flavescens, Ent. Brit. Byturus) eat both 
the petals and stamens of Stellaria holosteum; and Mordella wi open the anthers 
with the securiform joints of their palpi to get at the pollen. 
5 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 Zvans. Ent. Soc. Lond, ii. 214-224, 
Willd. Grundriss, 352. ‘ 6 Phil. Trans, xlvi. 536. 
