214 INSECTS INJURIOUS TO VEGETATION. 



Solutions of soap, or a mixture of soapsuds and tobacco- 

 water, used warm and applied with a watering-pot or with a 

 garden engine, may be employed for the destruction of these 

 insects. It is said that hot water may also be employed for 

 the same purpose with safety and success. The water, tobacco- 

 tea, or suds should be thrown upon the plants with considerable 

 force, and if they are of the cabbage or lettuce kind, or other 

 plants whose leaves are to be used as food, they should subse- 

 quently be drenched thoroughly with pure water. Professor 

 Lindley recommends syringing plants, as often as necessary 

 to remove the lice, with a solution of half an ounce of strong 

 carbonate of ammonia in one quart of water, which has the 

 merit of being clean as well as effectual. Lice on the extremi- 

 ties of branches may be killed by bending over the branches 

 and holding them for several minutes in warm and strong 

 soapsuds, or in a solution of whale-oil soap. Against the 

 depredations of the plant-lice that sometimes infest potato- 

 fields, dusting the plants with lime has been found a good 

 remedy. Lice multiply much faster, and are more injurious 

 to plants, in a dry than in a wet atmosphere; hence in green- 

 houses, attention should be paid to keep the air sufficiently 

 moist; and the lice are readily killed by fumigations with 

 tobacco or with sulphur. To desti'oy subterranean lice on the 

 roots of plants, I have found that watering with salt water 

 was useful, if the plants were hardy ; but tender herbaceous 

 plants cannot be treated in this way, but may sometimes be 

 revived, when suffering from these hidden foes, by free and 

 frequent watering with soapsuds. 



Plant-lice would undoubtedly be much more abundant and 

 destructive, if they were not kept in check by certain redoubt- 

 able enemies of the insect kind, which seem expressly created 

 to diminish their numbers. These lice-destroyers are of three 

 sorts. The first are the young or larvae of the hemispherical 

 beetles familiarly known by the name of lady-birds, and scien- 

 tifically by that of Coccinella. These little beetles are gener- 

 ally yellow or red, with black spots, or black, with white, red, 

 or yellow spots; there are many kinds of them, and they are 

 very common and plentiful insects, and are generally diffused 



