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nearly related group of insects, the plant lice, (aphididae.} 

 The methods of control that ure successful with these 

 insects are based upon this life habit of restricted x motility 

 and in the main consist of the use of what are known as- 

 "contact insecticides." These insecticides depend for their 

 killing power, not upon the introduction of some toxic 

 agent to the digestive tract of the insect, but upon the ef- 

 fect that the agency used may have upon the insect when in 

 contact with it externally. They may be caustic in their 

 action, actually destroying the tissues of the insect, and 

 so i inging about its death, or they may be oily in their 

 nature and depend for their killing power upon entering 

 the body of the insect through the breathing pores. These 

 are situated upon the sides of the body, and through them 

 and their connecting tubes, (tracheae), air is carried to all 

 parts of the insect's body. While the exact action of the 

 oily sprays upon the insect's respiratory system is proble- 

 matical, still the value of these sprays depends upon their 

 effect on this system. A third class of contact insecticides 

 depend for their value upon their tendency to loosen the 

 insect from its situation upon the plant and permit the 

 action of the weather upon the thus exposed pest to cause 

 its death. Each of the methods above outlined has its value 

 in particular cases and under certain conditions. 



CONTROL OP SCALE INSECTS. 



The two pests among the scale insects causing the great- 

 est losses in this state are the so-called San Jose Scale 

 (Aspidiotus perniciosus Comst.) and the New or West In- 

 dian Peach Scale (Aulacaspis pentagona Targ.) The San 

 Jose Scale is well distributed throughout the whole state 

 while the West Indian Peach Scale is not quite so wide- 

 spread in its distribution. Both insects belong in the group 

 known as the armored scales which means that the living 

 creature is covered over with an armor like shell which is 

 composed of the cast skins (exuviae) of the insect and of 

 a waxy material secreted by it. In both cases the individ- 

 uals are extremely small and it is only their great num- 

 bers that make them a dangerous pest. It is not our in- 



