MANUAL OF VEGETABLE- 

 GARDEN INSECTS 



CHAPTER I 

 GENERAL CONSIDERATIONS 



It was estimated by C. L. Marlatt in 1909 that the annual 

 loss caused to vegetable and truck crops in the United States 

 by insect pests amounts annually to 20 per cent of their value, 

 or $68,000,000. This sum includes the cost of insecticides and 

 other expense incurred in fighting vegetable insects. 



Insects affect vegetable crops in various ways. They feed 

 on the leaves, devour the roots, tunnel the stems and infest 

 the seeds and fruits. In many cases their injuries to succulent 

 parts of the plant give entrance to decay-producing organisms 

 which greatly augment the damage. Insects also act as carriers 

 of specific diseases, the most remarkable instances of this kind 

 being the transmission of the curly-leaf disease of the beet by 

 the beet leaf-hopper and the carrying over winter of the bacterial 

 wilt of cucurbits by the striped cucumber beetle. 



The enemies of vegetables here treated are, with five excep- 

 tions, members of that class of animals known as insects. These 

 exceptions are : the red-spider and the mite producing erinose 

 of the tomato, which are Arachnids ; snails or slugs, belonging 

 to the molluscs; millipedes belonging to the Myriapoda and 

 the root-knot nematode, one of the true worms. 



Some vegetable insects are general feeders, attacking a great 

 variety of plants, but the greater number are more or less 

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