292 INDIRECT BENEFITS DERIVED FROM INSECTS, 



crowded with dead or drowning flies 3 . What was the 

 object of this singular manoeuvre does not seem very ob- 

 vious. At the first glance one might suppose that, hav- 

 ing deposited an egg in the fly, it intended to avail itself 

 of the tube of the leaf instead of a burrow. Yet we know 

 of no such strano-e deviation from natural instinct, which 

 would be the more remarkable because the insect was 

 European, while the plant was American and growing in 

 a hot-house. And at any rate it does not seem very like- 

 ly that the insect would commit her egg to the tube with- 

 out having previously examined it; in which case she 

 must have discovered it to be half full of water, and con- 

 sequently unfit for her purpose. — It is not so wonderful 

 that many large flies should, as Professor Barton informs 

 us, drop their effo-s into the Ascidia furnished with dead 

 carcases : and it seems very probable that Dytisci oviposit 

 in them ; for the Squilla which Rumphius found there 

 was probably one of their larvae, this being the old name 

 for them b . 



However problematical the agency of insects caught by 

 plants as to their nutriment, there can be no doubt that 

 many species perform an important function with regard 

 to their impregnation, which indeed without their aid 

 would in some cases never take place at all. Thus, for 

 the due fertilization of the common Barberry [Berberis 

 vulgaris) it is necessary that the irritable stamens should 

 be brought into contact with the pistil by the application of 

 some stimulus to the base of the filament ; but this would 

 never take place were not insects attracted by the mellife- 

 rous glands of the flower to insinuate themselves amongst 

 the filaments, and thus, while seeking their own food, un- 

 a Smith's Introduction to Botany, 195. b Mouffet.. 319, 



