250 INJURIOUS AND USEFUL INSECTS 



are feeding upon low plants. Shaking of boughs is sometimes 

 a means of dislodging great numbers of insects, esjiecially 

 beetles, which are to be caught in sheets and destroyed 

 immediately. 



Hand-Picking 



In a few cases this is the least laborious way of removing 

 insects. Nothing is so effectual a remedy against the goose- 

 berry saw-fly as picking off every leaf that has eggs on it. 



Change of Crop 



This is often the best remedy for an obstinate pest, and is 

 a useful preventive, even when insects are not troublesome. 



Encouragement of Crop 



Where a young crop is threatened by the attacks of insects 

 good manuring will often help it through until it has strength 

 enough to stand the loss, or until the insects cease to feed. 



Insectivorous Birds 



Birds of all kinds are best let alone where only field-crops 

 are grown. Nets are often necessary to protect fruit. 



Insect-destroying Fungi 



Inoculation with bacteria or moulds sometimes, under natural 

 conditions, sets up deadly disease among caterpillars, and this 

 has suggested that destructive caterpillars may be infected by 

 laying infected matter among them. The method has not yet 

 been sufficiently experimented with to give results of practical 

 importance. 



Egg Destruction 



Where the eggs of an insect-pest are collected in visible 

 patches they may sometimes be destroyed very rapidly with 

 fire, petroleum, or creosote (p. 241). 



