272 CONTROLLIXG INSECTS AND DISEASES 



Other insects possess mouth parts which permit them to 

 lap or lick up liquids from the outer surfaces of the object on 

 which they feed. The adult fly of the apple maggot and the 

 cherry fruit fly are illustrations. 



As the insect passes through dift'erent stages of develop- 

 ment (metamorphosis) , it may possess dift^erent types of mouth 

 parts. The larva or worm has biting mouth parts whereas the 

 adult moth may lap up its food as in case of the apple maggot. 



(6) Consider the Nature of Disease Attacks. Fruit dis- 



FiG. 101. Some insects with sucking mouth parts, (a, h, c, d, e) Scale 

 insects. (/) Leafhopper. {g) Plant Bug. (/i) Aphids. 



eases, with a few exceptions, are of the fungus type, plant 

 forms lacking the chlorophyll or green coloring matter of 

 common plants and existing as parasites in or on the tissues 

 of Wxing plants. x\pple scab and bitter rot are examples. 

 Propagation takes place by means of the development of seed 

 forms called spores. The wind — including even light air cur- 

 rents — rain, insects, and other agents are responsible for 

 their dissemination. Fungi need moisture for a period in order 

 to develop from the spore stage and to establish themselves 



