INJURIOUS INSECTS AND DISEASES 289 



house is kept hot, dry, and badly ventilated. The colour is various, depending 

 on the nature of the food ; possibly, also, in some degree on the age of the 

 individual. The attacked leaves may be known by their greyish marbled 

 appearance above, w^hile beneath they are whitish and slimy from the covering 

 of the web. The red spider is most injurious to vines in hot, dry weather, 

 consequently washing and syringing, which will render the leafage and ground 

 moist, are serviceable. The extreme dryness of the air and soil are thus 

 counteracted and a healthy growth encouraged, which more or less counter- 

 balances the injury to the leaves from the suction of the mites. It is important 

 to check the attack at the very beginning, and for this purpose syringings 

 morning and evening are advised, sent hard at the under side of the leaves so as 

 to break the webs and wash them down with the contained mites. Sulphur 

 and soft soap combined in various ways are the most reliable remedies. 



Thrips [Thrips minutissima). — This insect is of a dark brown colour or 

 almost black. It feeds upon the leaves of the vine, thereby interfering with the 

 proper elaboration of sap, and being a dirty insect it soon spoils the fruit. Like 

 the red spider it flourishes best in a dry atmosphere. If taken in time sponging 

 with kerosene emulsion will be found a thoroughly effective remedy. 



Mealy Bug {Dactylopius adonidum). — This pest is one of the most trouble- 

 some met with in vine culture. When once introduced it spreads from the 

 branches to the shoots, and thence to the fruit. A good remedy is to apply a 

 coating of methylated spirits with a soft brush. Fir tree oil and paraffin in a 

 diluted form also cause death to the pests. 



The Vine Louse {Phylloxera vastatrix). — Of all the insects with which the 

 grape grower has to contend this is the most terrible, and no certain remedy for 

 its destruction has yet been discovered beyond that of taking out all the vines 

 and burning them, together with the soil in which they grow, thoroughly 

 cleansing, painting, and lime- washing the houses, then replanting with fresh 

 vines. 



CUCUMBER AND MELON 



As recently as 1896 a new species of leaf-blotch has been found to attack 

 both the cucumber and melon. The fungus has been named Cercospora melonisy 

 and it has spread with such remarkable rapidity that at the present moment it 

 is one of the most destructive parasites with which the cultivator of cucumbers 

 and melons has to contend. 



The foliage is the first part attacked. At a later stage the fruit often also 

 suffers. The first indication of the presence of the disease is the appearance of 

 a few small, scattered, pale green spots on the upper surface of the leaf. The 

 spots gradually increase in size and also in number, and often run together, 

 gradually passing through grey to a brownish colour. If at this stage the upper 

 surface of the diseased spot be examined with a pocket lens, it will be seen to 

 be covered with delicate upright brown threads, each bearing a conidium at 

 its tip. This represents the fruiting portion of the fungus, the mycelium 

 or hypse being buried in the substance of the leaf. The minute conidia 

 or reproductive bodies are carried from diseased to healthy leaves by currents 



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