272 BEES AND BEE-KEEPING. 



show that they are provided with two short tubes, 

 called the nectaries («, A, Fig. 54), by which they 

 are enabled to eject a sweet fluid. 



Leaves are constantly forming starch, which is at 

 once converted into the soluble form, sugar ; so that 

 the Aphis is, perhaps, provided with saccharine sub- 

 stances in such quantity that the excess must be 

 drained off. Standing, two or three years since, in the 

 shadow of a lime tree, I saw falling, in the sunlight, 

 a thick, constant shower of minute drops, which were 

 being expelled from the anal apertures and nectaries 

 of the Aphides infesting the leaves. The necessity 

 for this vigorous ejection is apparent ; without it, the 

 closely -packed colonies would soon be hopelessly 

 fixed to the leaf, and to one another. The grass be- 

 neath the tree was thickly gummed, while the upper 

 surface of every leaf was closely covered, and not 

 a few bore incipient drops at their points. Other 

 instances quite as remarkable have attracted my 

 attention ; in one case, that of a sycamore, overhanging 

 some paving-stones, the latter were rendered actually 

 dangerous to the pedestrian ; and one of my apple 

 trees ("Sturmer Pippin"), this summer, became, in very 

 few days, so covered, that every leaf carried hundreds 

 of the Aphis Mali, and every fruit was running with 

 what might have passed as a compound of treacle and 

 soot. Few botanical families appear to be altogether 

 proof against the attack of these pests, which are all 

 but universally distributed, and of which Beckton,* in 

 his magnificent work, describes about 300 distinct 

 species, the oak suffering from about six, the birch, 

 * "Monograph of the British Aphides," Ray Society, 1883. 



