^^ THE CANADIAN HORTICULtURISl'. 



SOME EELATIONS BETWEEN PLANTS AND INSECTS. 



BY JOHN ELKINGTOX, M.D., OMPAH, OXT. 



■Sir Jno. Lubbock, F. U.S., lately delivered a most interesting lecture 

 <on the above subject, in Leeds, England^ some portions of which have 

 a special interest to the hybridist ; and though it is not possible in 

 these pages to reproduce the whole discourse, I have thought a selec- 

 tion from the report in the English Aynadtural Gazette might give 

 profitable food for thought to readers of the Candian Horticulturist. 



The lecturer alluded to the diffierence existing in plants, not only 

 differences in form, size and color, l)ut also in other respects, some 

 being hairy, glutinous, stick}^, &c. These may be accounted for in a 

 great measure by the relations borne by plants to insects, the visits of 

 which are generally necessary to ensure the fertilization of one flower 

 by the pollen of the other. In some cases, liowever, such as that of 

 Drosera, the object of the flower is to attract insects for tlie, purpose of 

 devouring them, and therefore the leaves are covered witli sticky hairs, 

 which bend gradually forward when an insect alights on the leaf, and 

 squeezes it slowly to death, its juices going to the nourishment of its 

 alluring and deceitful foe. 



It is easy to see the advantage which flowers gain from secreting 

 honey, inasmuch as they are dependent for fertilization on the visits 

 of bees and other insects, which while feeding necessarily dust them- 

 selves with pollen, and thus carry it from flower to flower. But it is less 

 easy to understand why honey should be secreted on those parts of 

 flowers where no pollen exists, at the base of the leaf-stalks, for 

 instance. For the explanation of this we are indebted to Mr. Bell, 

 and Mr. Delphine, who observed that in some cases upon the stems, 

 and living upon the honey, exist colonies of small ants, constituting a 

 most efficient body-guard against the attacks of leaf-cutting ants. 

 They also protect plants from the attacks of many other enemies, and 

 are in their turn made use of by various small sj^ecies of Aphides who, 

 by secreting a sweet fluid, of which they allow the ants to avail 

 themselves, convert them from enemies into friends and thereby secure 

 a cordial, instead of an angry reception. 



Harmless, however, and even useful as are ants which confining 

 themselves only to the stalks of flowering plants, they Avould generally 



