GENERAL PRACTICE. ENEMIES. 257 



and around their nests drives ants away. A broad thick chalk line around the stems of 

 trees prevents their passage. Petroleum sprinkled over their nests kills or drives away 

 ants. Ammoniacal liquor diluted with six times its bulk of water is also effectual, as 

 is a decoction of quassia chips, 4 ounces, being boiled a quarter of an hour in a gallon of 

 water, and 4 ounces of soft soap added as the decoction cools. A strong decoction of 

 dwarf elder (Sumbucus ebulus) leaves poured on the nest at night destroys it ; and a 

 piece of camphor the size of the thumb end to the first joint, dissolved in \ gallon of hot 

 water, poured over the nest, or applied to trees in pots infested with ants, is effectual. 



In spring, ants are best disposed of by mercurous chloride : calomel, 1 part ; 

 finely -powdered loaf sugar, 11 parts; mix these together, lay them in little heaps in their 

 haunts ; the ants eat the compound and perish. This is the least objectionable of drastic 

 measures, but the following must be used with very great care, never entrusting the 

 poison to any but most cautious persons. Arsenic trioxide (common or white arsenic), 

 1 ounce ; boil in an iron pot with a quart of water until reduced to half, then add J 

 pound of brown sugar, stirring well. Drop on pieces of slate, or place in saucers, and 

 set these about the nests, and the sweet-toothed marauders will have their last meal, 



Aphides. These insects are noted for their destructive effects upon vegetation. 

 They live on the juices of plants and trees, impair their vitality, and injure, if not spoil, 

 the crops of fruit. The pests cause the leaves to curl, and the tender growths become 

 stunted and distorted. The injury inflicted is, of course, proportionate to their number 

 and the time they are allowed to infest the trees. 



Aphides possess short oval bodies, six legs, and a pair of antenna. When wings are 

 developed, the front pair are membranous throughout their entire extent. The insects 

 have glandular structures which secrete a sweet viscid fluid (see "Ants"). These secretions 

 blacken the bark, close the pores, causing the parts coated to become sickly and exhale 

 a disagreeable smell. The colour of aphides varies with different species. Apple and 

 pear aphides, Aphis mali or pyrimali, are grass green, but the colour changes with 

 different broods. The first are dark slaty grey, mottled with green ; later generations are 

 green, dirty yellow, or rusty, their tints evidently being affected by the juices of the 

 trees upon which they feed. Some species, however, are decided in colour, notably that 

 selected for illustration. 



Black Fly (Aphis cerasi) is a very dark brown or shining black. It infests the under 

 side of the leaves, points of the shoots, young growths, and trusses of fruit of tne 

 cherry, as represented in the engraving on next page. 



VOL. I. L L 



