THE PESTS OF THE FARM. 9T 



sometimes is assailed by a number of species at once, and 

 almost eternal vigilance is necessary for the successful cultiva- 

 tion of nearly all our crops. Fortunately the Creator has pro- 

 vided numerous assistants for man in the work of protection, 

 and most of the birds, many of the mammals, as we have 

 already found, and whole families of the insects, are continually 

 at war against the noxious ones. 



Did my limits permit I would designate a few of the most 

 valuable carnivorous insects, and show how and to what extent 

 they are beneficial, but with a brief general recommendation 

 for the dragon flies, which are carnivorous, feeding almost 

 entirely upon noxious insects; for the tiger beetles, (those 

 active beetles which frequent sandy plains and roads, and 

 when forced to take flight alight after passing a short distance 

 and turn to face the intruder,) which destroy great numbers of 

 small lepidoptera and larvaj ; and for the ichneumon flies which 

 lay their eggs in the bodies of lepidopterous and other larvas, 

 the grubs of which when hatched devour the caterpillar that 

 incloses them ; I will pass to the most prominent of our noxious 

 insects. 



Of the species which attack our various fruit-trees, none of 

 late years have proved more destructive than the canker-worm. 

 This worm is the larva of the canker-worm moth, the male 

 only of which species is furnished with wings. The history of 

 this insect is now pretty well known ; but for the information 

 of those who have had no opportunities of observing its habits, 

 I will present the account given by Dr. Harris : — 



" It was formerly supposed that the canker-worm moths came 

 out of the ground only in the spring. It is now known that 

 many of them rise in the autumn and in the early part of win- 

 ter. In mild and open winters, I have seen them in every 

 month from October to March. They begin to make their ap- 

 pearance after the first hard frosts in the autumn, usually 

 towards the end of October, and they continue to come forth in 

 greater or smaller numbers, according to the mildness or sever- 

 ity of the weather after the frosts have begun. Their general 

 time of rising is in the spring, beginning about the middle of 

 March, but sometimes before and sometimes after this time ; and 

 they continue to come forth for the space of about three weeks. 

 It has been observed that there are more females than males 



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