THE FLORAL WORLD AND GARDEN GUIDE. 51 



creating a current of fresh air through the house by opening top 

 and bottom ventilators, which in its cour.se dispels damp, conveying 

 at the same time health and vigour to tlie occupants of the house. 

 Extreme and sudden variations of temperature is another cause of 

 the production of green-fly ; it should therefore be avoided as much 

 as possible, not only to guard against its appearance, but also 

 as injurious to the maintaining of all plants iu a healthy vigorous 

 condition. 



The Mealy Bug and White and Brows" Scale are, with the ex- 

 ception of thrips, perhaps the worst pest which any valuable collection 

 of plants can be infested with. They are decidedly the most difficult 

 to exterminate, for nothing but difficult and tedious measures will 

 avail. To prevent their making an appearance, the utmost caution 

 is necessary. Have a vigilant eye upon all new introductions before 

 they are introduced into the house among other plants, by seeing 

 that they are properly cleansed of all insects with which they may 

 be infested. The structures in which they are grown should also 

 be scrupulously clean. It is astonishing what clean water and a 

 little of the right sort of labour will do to maintain all plant-houses 

 in a sweet, wholesome condition, if they are otherwise properly 

 managed. Cobwebs hanging here and there, and crevices full of 

 dust and dirt, and patches of mortar hanging from the walls, are the 

 places in which many of the worst enemies of the gardener find 

 comfortable winter quarters. They ought, therefore, not to be allowed 

 to exist, as the surest means of not affording vermin any snug corner 

 in which they may lodge themselves until a more favourable season 

 draws them ibrth to begin life afresh. A deficiency of light during 

 the short dark days of winter is also favourable to the spread of 

 these pests; a judicious distribution of the plants, so as to offer the 

 least obstruction to its rays penetrating all parts of the house, should 

 be carried out, and also see that the glass, both on the roof and 

 sides, is free from dirt, and not half-covered with film, as we some- 

 times see it. 



The Thhips are destructive pests, especially amongst azaleas and 

 vines, and none are more troublesome to get rid of. A dry, con- 

 fined atmosphere is sure to bring an attack of them, as also will a 

 neglect of the precaution of frequently syringing those subjects 

 which are most liable to be attacked by them. But perhaps the 

 thrip is nowhere more perplexing than when it shows itself in the 

 fernery, which it s(wnetimes does amongst stove-ferns, the result, 

 i'requently, of too dry an atmosphere and an insufficiency of air. 

 But more generally it is brought into the house by some addition 

 to the number of plants, either from the nursery or some other 

 garden. It is therefore the safest plan to subject each new-comer 

 to a series of gentle smokings with tobacco previous to placing it in 

 the collection. 



The Ked-spider is unfortunately too well known, as we may 

 sometimes find it in the best-conducted gardens. Indeed, it is not 

 always possible to keep it under, and there are so many circum- 

 stances favourable to its production, that we really cannot seriously 

 find fault if we see it occasionally obtaining the mastery over the 



February. 



