50 TUE FLORAL WORLD AND GARDEN GUIDE. 



DEFIANCE TO GREENHOTJSE EOES. 



BY GEOEOE SMITH. 



IITH the return of genuine spring weather the various 

 insect pests which usuall}' attack greenhouse plants 

 will become active; and if the plants were badly in- 

 fested last year, they will occasion the amateur an 

 immense amount of anxiety and considerable bard 

 work to keep them in subjection. In almost every instance the 

 presence of iusect pests is an indication of neglect or bad munage- 

 ment ; for when the plants are properly attended to, it is seldom 

 indeed that the plant-pests occasion much trouble. They do not 

 often put in an appearance in sufficient numbers to do much harm 

 when the house is kept thoroughly clean, and the plants in a thriving 

 condition. As "prevention is better than cure " in this case, as in 

 many others, I purpose offering a few remarks on the pests which 

 give the most trouble to the amateur by reason of their persistency 

 and the mischief they do when they attain a firm foothold, and I 

 hope to be able to point out the way by which they may be pre- 

 vented from obtaining a foothold in the plant structure. 



In the first place, it is necessary to say that one of the chief 

 causes which will speedil}- produce cue or more of the enemies 

 which will be mentioned as we proceed, is disregard to the common, 

 rules of cleanliness in the management of structures. Dirty pots, 

 grimy stages, and moss-covered soil, with an accumulation of decay- 

 ing leaves in and about the plants, Avill soon be the means of the 

 inmates of the house becoming infested with various kinds of insects 

 that will speedily cripple their grovvth, and not only spoil their 

 beauty, but endanger their lives, if unmolested. Another fruitful 

 source which is highly favourable to the attack of mildew and the 

 production of green-fly, is a stagnant atmosphere, produced by 

 keeping the house closed during dull damp weather, more especially 

 if the temperature is mild, and the outward atmosphere quiet, and 

 loaded with moisture, as was the case on several daj'S during 

 last month. 



Green-plt. — Some amateurs fail to see the necessity of ventila- 

 ting their greenhouses unless the sun is shining brightly, so they 

 keep them shut up on still, mild, cloudy days, under the false impres- 

 sion that the plants do not need fresh air ; in fact, they believe they 

 would be better without it, and for days together they are conse- 

 quently enveloped in a stagnant atmosphere, which is extremely 

 hurtful. This is injurious in a high degree, as, if it does not directly 

 produce an attack of green-fly, it indirectly renders them liable to 

 be attacked, as, being in a weak, succulent condition, brought about 

 by an insufficiency of fresh air, they have not the health and vigour 

 to withstand their ravages, as have those of more robust and hardy 

 constitution. The most careful cultivators change the internal air 

 of their houses as frequently as possible, by starting a good brisk 

 fire for two or three hours early in the mornings of dull days, thus 



