INSECTS INJURIOUS TO GRAPE VINES. 



107 



are not well ventilated will be more subject to red-spider than the 

 freely-ventilated parts. It follows, therefore prevention being better 

 than cure that as dryness is the chief cause of its appearance, so 

 moisture and water properly supplied ought to prevent it ; and it is so. 

 Hence, we may deduce the following rules : Water freely, and keep 

 the atmosphere at all times thoroughly moist whilst the Vines are 

 growing, especially if the temperature be high. If these points are 

 attended to, little injury from red-spider need be feared in the case 

 of Vines otherwise healthy. If, unfortunately, it does obtain a 

 footing, water must still be the chief agent with which to compass its 

 destruction ; therefore, syringe freely with clear rain-water, also apply 

 sulphur to the hot-water pipes, or dust the leaves over with 

 sulphur, etc.; or wash them with soapy water, with a decoction of 

 quassia-chips, or with any compound of sulphur and soap. These 

 remedies, applied with perseverance, will be sure to destroy it. 



The Thrips (TJirips minutissima), fig. 42. The figure shows the 

 thrips much enlarged. It is a small, long, slender insect of a dark 

 brown colour, sometimes pallid or almost white, which is oftentimes to 



be found feeding upon 

 the Vine leaves much 

 in the same manner as 

 the red-spider. The 

 thrips is, however, not 

 so generally to be found 

 on Vines as is the red- 

 spider, and would rather 

 appear to be introduced 

 to the Vineries from 

 other plants ; but its 

 ravages are much more 

 severe where the insects 

 are permitted to establish themselves, and they spread rapidly. A 

 dry atmosphere is favourable to their increase, and in like manner 

 water is inimical to them ; but they can scarcely be dislodged or 

 destroyed by any amount of mere syringing. It is necessary to wash 

 the leaves with soap and sulphur, or to give them a good dressing 

 with tobacco-powder or some insecticide, but it must be applied 

 directly to them or it will be of little avail. 



The Mzaly Bug (Dactylopius adonidum), fig. 43. This is an 

 insect of foreign introduction, but it is now, unfortunately, very 

 common in our plant houses. It seems to be at home on most plants, 

 and so the Vine does not escape it. The mealy-looking substance 

 which covers the body of the insect is an excretion, and gives rise to 

 the name of mealy bug. Its first appearance in a Vinery ought to be 

 rigorously guarded against, and no plant with any bug on it should 

 ever be taken into a Vinery, for if once introduced it is scarcely 



Fig. 42. THRIPS, ENLARGED. 

 The natural size indicated by the cross lines. 



