APPLE LEAVES, PLANT-LOUSE — HONEY DEW. 53 



from rains and the night dews. The leaf-stalks also become bent, 

 so that all the leaves growing upon a twig are, in badly-infested 

 trees, turned backwards, pressing against the twig, and thus 

 shielding that part of the colony which is located thereon. An 

 infested tree may be distinguished at a distance of several rods 

 by the leaves on the ends of its twigs being thus turned back- 

 wards, instead of standing freely out in their natural position. 

 The bark of the limbs, and the surface of the leaves also, becomes 

 blackened as if it had been smoked by the flame of a candle or 

 other burning substance. This blackness does not rub off upon 

 white paper, but Mr. Briggs informs me that washing the bark 

 with a solution of sal soda removes it entirely. He had observed 

 this black appearance of his trees before he noticed the lice which 

 caused it, and seeing a newspaper-recommendation of this wash 

 for cleansing trees, he applied it to four of those in his orchard. 

 The next day he was astonished at finding myriads of these lice 

 crawling down and up the trunks of these four trees, and upon 

 the ground they were heaped together in a ring around their 

 bases. The alkaline matter in this wash had evidently tinctured 

 the sap of the tree, and made it unpalatable to these insects, and 

 they endeavored to emigrate to some place free from it, but on 

 reaching the ground they knew not where to go, and many, there- 

 fore, travelled up the trunk again in search of some other avenue 

 of escape. 



A strong disagreeable smell is also emitted from trees that are 

 badly infested with the apple-plant louse, and when a person has 

 been examining infested twigs this smell remains upon his hands. 

 The odor is peculiar and very loathsome, and reminds me of the 

 smell of stale fish more than anything else with which I am able 

 to compare it. 



All the insects of this family secrete copiously a sweetish fluid, 

 called honey dew. This is ejected from the two little horns, or nec- 

 taries, which project one on each side of the hind part of their 

 bodies. Often a clear drop of this fluid may be seen at the tip of 

 one or both of these horns. This fluid, falling upon the leaves 

 and evaporating, gives the leaves, under a colony of these lice, a 



