14 



FUMIGATION INVESTIGATIONS IN CALIFORNIA. 



Mealy bugs occur in various parts of the southern end of the State. 

 Tlieir appearance is usually spasmodic and in restricted areas. These 

 insects are at present more serious than elsewhere in Ventura County, 

 where they occur in great numbers. 



The citrus red spider is general in distribution, whereas the silver 

 mite is restricted to the region about the city of San Diego. 



INJURY RESULTING TO SCALE-INFESTED TREES. 



In scale insects the mouth is an elongated beak or tube. This 

 tube is inserted into the bark or covering of the host plant when the 



insect is feeding, 

 and is used to draw 

 up the plant juices, 

 which are the scale- 

 insect's only food. 

 When great num- 

 bers of these insects 

 draw sap from the 

 tree, even though 

 they are very mi- 

 nute, the tree's 

 vitality is greatly 

 reduced. This ef- 

 fect is very marked 

 in the attacks of 

 the red and purple 

 scales. Both of 

 these species cause 

 much destruction, 

 yet the writer is of 

 the opinion that the 

 red scale will de- 

 stroy a citrus tree 

 in less time than 

 will the purple 



Fig. 6.— Orange tree almost destroyed by red scale. (Original.) scale all other fac- 



tors being equal. Trees have been noticed from two to three years 

 after planting which had been killed by the red scale. Large 

 orchard trees are frequently destroyed by the pest (fig. 6), while it 

 is a very common sight in regions of severe infestation to see large 

 branches killed back to the trunk. Although no trees have ever 

 come to the writer's attention wdiich were completely killed by the 

 purple scale, severe infestations result in the destruction of many 

 branches (fig. 7), and cause such a drain on the tree that the produc- 

 tion of fruit is greatly decreased. Moreover, the purple scale spreads 



