466 CALIFORNIA FRUITS I HOW TO GROW THEM 



Insects of California," by E. O. Essig, State Board of Horticulture, 

 Sacramento, 1913. Furthermore as the study of the pests and the 

 invention of means for their destruction are continually progressing 

 one can only keep himself up to date and enable himself to profit by 

 improvements, by diligent reading of California's periodicals devoted 

 to practical horticulture. 



CLASSES OF INSECTS 



In order to arrange injurious insects in classes in a popular way, 

 the grouping here will be based upon the character of the work they 

 do. This arrangement has been followed by other writers and is 

 perhaps better than attempting to group the insects which prey upon 

 any single tree or plant, because injurious insects seldom restrict 

 themselves to a single food plant. Therefore the grouping will be as 

 follows : 



(1) Insects destroying foliage; 



(2) Insects upon the bark or upon the surface of leaf and fruit; 



(3) Insects boring into the twig, stem or root; 



(4) Insects boring into the pulp of fruits. 



INSECTS DESTROYING FOLIAGE 



Cut Worm's and Army Worms. These are the larvae of Noc- 

 tuid moths, which often become abundant over limited areas and 

 do much damage to trees and plants. Cut worms and Army worms 

 are terms applied to the same insects in California. In ordinary years 

 they are not present in sufficient numbers to cause much concern, and 

 in such years they are known simply as cut worms. When all condi- 

 tions are favorable, however, certain species develop in enormous 

 numbers and having exhausted the food supply where they breed, they 

 begin to migrate or march, commonly in a definite direction, as an 

 army in search of new food. When they thus appear in such large 

 numbers and take on the migrating habit they are called army worms. 



Some of the caterpillars have the habit of climbing up vines and 

 trees and eating off the buds in the early spring. These are called 

 climbing cut worms. Others remain at or near the surface of the 

 ground and feed by cutting off the plants at this point. They are 

 more commonly found in the grass lands, but very frequently attack 

 cultivated crops, particularly on land that was in grass the previous 

 year. 



Of the methods used to protect trees and plants from cut worms, 

 poisoned bait is probably the most common. This consists of bran 

 and molasses or other sweet substance poisoned with arsenic and 

 distributed in handfuls about the plants. The proportions are as 

 follows : forty pounds of bran, two gallons of cheap molasses, and 

 five pounds of arsenic. Cheap glycerine may be used to prevent the 

 mixture from drying. This will be eaten by the worms in preference, 

 usually, to the plants which it is desired to protect. 



