INSECTS THAT INFEST ORCHIDS. 55 



smooth or glazed pans, so that the sides are in a slanting posi- 

 tion, and fill them with treacle and water, in which the insects 

 drown themselves. Woodlice may be destroyed by placing Pota- 

 toes cut in halves about the plants, which should be examined 

 every day till they disappear. Green-fly may be killed by 

 smoking, but it must be done very carefully with good tobacco 

 paper, or the leaves of some will suffer. If to 1 Ib. of tobacco 

 paper, 1 oz. of saltpetre be dissolved in water by boiling it in a 

 small pan, and sprinkled over the paper, or the paper soaked 

 in it, it doubles the strength of the paper without much in- 

 creasing the risk of burning, still only half the quantity must 

 beused, andif a certain weight be not strong enough for a house, 

 it may be gradually increased. Three smokings on successive 

 nights will kill thrips ; or for either thrips or spiders, if the 

 plants be washed with a mixture of 1 oz. of bitter aloes and 

 1 oz. of tobacco to a gallon of water, it is safer than mixtures 

 containing soft soap or turpentine, which are apt to burn the 

 plants or spoil the leaves if it gets in the crowns. Tobacco 

 water made from pure tobacco in bond, free of duty, may be 

 had at many places, and at the nurseries at 3s. 6d. per gallon. 

 They should be washed immediately on its appearance, and the 

 plants examined a time or two about once a week after, and if 

 done as soon as seen, and not allowed to spread, there is little 

 difficulty in keeping them clean. Ants may be destroyed by 

 a few fresh, unpicked bones being placed for them, or sponges 

 wetted and filled with sugar, or treacle in bottles or pans. 

 Slugs may be collected by a little bran placed under some Cab- 

 bage leaves, or pieces of bark with the hollow side down, which 

 is also a good trap for woodlice. 



