230 State Horticultural Society. 



SAN JOSE SCALE. 



(By Dr. J. M. Stediuan, Prof, of Entomology, Oolunibia, Mo.) 



I addressed this Society on this same subject seven or eight 

 years ago, but have been experimenting these later years, and 

 thought it a fit subject to again consider. I do not think it is nec- 

 essary to rehearse the complete life history of this insect at this 

 time. 



The insect, when full grown, is one-fourteenth of an inch in di- 

 ameter. The bulk of the insects we see on the tree are not adult in- 

 sects, and are, therefore, much smaller than this. They are circular 

 in shape, quite flat, with a dot or spot in the center. As a rule, 

 the scales we see on a tree are the females. The San Jose scales do 

 not lay eggs; they bring forth living young, which run around 

 for a few hours, then stick their bills in the tree and begin to ex- 

 crete a scale which covers their body. The females never move 

 again. The males later have wings and fly about. Probably you 

 ihave never seen one of them. They are very small and hard to- 

 see. The scale on the females finally bcomes much larger than the 

 insect itself. A single female, hibernating over winter, will result 

 in the production, by fall from her offspring, of three thousand 

 million scales, 65 per cent of which will be female. Not all of 

 these live, of course; but this is possible. 



This scale infests practically all deciduous trees and plants. 

 It is regarded as the most serious and most dangerous enemy to the 

 fruit tree we have to deal with. One reason that it is so serious 

 is that it infests so many kinds of plants. Another reason is that 

 fruit trees are very susceptible to the attacks of this scale, which 

 injects a little poison into the cambium layer, and in three or four 

 years the tree is gone. It is rather difficult to kill this scale under 

 ordinary conditions. However, I do not wish to work up any feel- 

 ing against the insect which will make you think you have got to 

 give up growing trees. At first some did have this sentiment, but 

 now we have learned m.ore about this enemy. 



We must face the fact that the insect is here, and to stay, and 

 that it is multiplying and spreading fast. We can't absolutely get 

 rid of it, but we must make the best of it and fight it down. We 

 have it, and it is going to increase, and we must fight it just as we 

 fight other insect pests of various kinds. I do not mean that every 

 one who grows trees will have the scale, at least for many years. 



