INTRODUCTION. 7 



wood, a protective coating, after cleaning, is spread on the surface of 

 the wood, which preserves the wound from contact with the air, but 

 if there be a living piece of bark (parenchyma, cortical fibres, or liber), 

 whether in the heart of the wood or on its edges, it must be respected 

 and protected by some folds of the suberose layer. In this latter case, 

 the application of a coat of tar would be fatal, especially if used hot. 

 The artificial wound method is practised to restore health to a tree 

 whose bark is invaded by scolytus. Longitudinal incisions are made 

 on the parts attacked, penetrating the cortical layers only as far as 

 the liber. In serious cases, a narrow band is removed from the 

 suberose layers. This superficial incision induces a flow of sap, leads 

 to the formation of new tissue, and stops the transversal progress of 

 the larvae of the scolytus. If the tree has been invaded in all parts 

 by scolytes, the great part or even the whole of the circumference of 

 the tree is decorticated but so as not 'to wound living tissue. When 

 the strips are removed, hems are formed ; when the tree is completely 

 decorticated, a network of cortical fibres is seen to form on the sur- 

 face, the diameter of the tree grows, and a new bark is formed. 

 Surgical interventions of this kind, although rarely employed, may 

 be useful when chemical treatment has no effect. 



Methods of Destroying Parasites by the Naked Hand.— When 

 a parasite is of appreciable size, and especially when it forms visible 

 and accessible colonies, its suppression by catching gives immediate 

 results. On a large scale the parasites may be induced to localize 

 themselves in spots where their destruction is easy. According to 

 circumstances the methods used are (1) Picking or catching, (2) Traps 

 or baits. 



Picking and Catching. — Coleopterous insects (cockchafers), grubs 

 of butterflies, especially when they live in colonies, the agglomeration 

 of eggs of certain Bombyx (Ocneria) are picked. This picking is gener- 

 ally done by hand. However, when it is desired to pick small insects 

 rapidly, tinned iron funnels with a wide mouth are used, above 

 which the infected organs of the plants are shaken. The neck of 

 the funnel is connected with a cloth sack into which the parasites 

 fall (altise of vine). The gathering of insects on farm land is also 

 accomplished by aid of poultry. For this purpose there are portable 

 hen-houses, which are drawn into the middle of the fields. The 

 poultry wandering about at will soon free the plants and the soil from 

 all their parasitic insects. It is a very cheap, useful and ready 

 method.! 



Traps and Baits. — To facilitate the collection of insects and their 

 larvae artificial shelters fixed on the plants have been tried. The 

 trunks of trees in autumn have been girdled half-way up with un- 

 dulating cardboard bands of about four inches wide or with bands of 

 straw. All the insects which hibernate as perfect insects take refuge 

 there. All that has to be done is to remove and burn the refuges. 

 This process is of frequent use in Germany to destroy the vermin of 

 fruit trees. 



1 Translator's iV^oi!e,— Neither British farmers nor British gardeneis take kindly 

 to poultry, and both would regard the cure as worse than the disease. 



