S6 3IASSACHUSETTS HORTICULTURAL SOCIETY. 



out nurseiy stock north, south, east, and west, and a certain pro- 

 portion of this stock carried upon it the San Jose scale. The scale 

 was not recognized until the summer of 1893, when I found it 

 upon some pears from Charlottesville, Va. Since that time my 

 investigations have resulted in the ascertaining of nearh* two 

 hundred jioints in which the scale has established itself and be- 

 come destructive. Not one of these points is in territory which . 

 clearly belongs to the transition life zone, and 3'et who can ques- 

 tion the statement that thousands and thousands of young trees 

 bearing this scale must have been sold to fruit growers located 

 within this region, and have been planted by them. 



Even considering the San Jose scale by itself, the evidence is 

 entitled to great consideration, and to my mind is sufficiently 

 strong to form a basis for a guarded prediction. But it must be 

 further remembered that this is but a single instance among very 

 many known to us, and that it is upon the mass of facts we are 

 basing our knowledge of the indications of the general laws which 

 govern the geographical distribution of species. 



There are, however, localities in your State where the San Jose 

 scale and the West Indian peach scale are liable to do great dam- 

 age, and it thus becomes necessar^^ for fruit growers to inform 

 themselves about both species. I have now in proof a complete 

 bulletin referring to the whole subject of the San Jose scale, 

 which it will give me pleasure to send to any members of this 

 Society who care to apply for it, so that it will not be necessary 

 here to treat of this insect at any great length. 



The life histor}- of all scale insects may be briefly summarized 

 very much as follows : 



The eggs are laid by the adult female either immediately be- 

 neath her own body or at its posterior extremity. Certain 

 species do not lay eggs, but give birth to living 3'oung, as do the 

 plant lice. This abnormal habit is not characteristic of any par- 

 ticular group of forms, but is found with individual species in 

 one or more genera. The young, on hatching from the eggs, are 

 active, six-legged, mite-like creatures, which crawl rapidly away 

 from the body of the mother, wander out upon the new and ten- 

 der growth of the tree, and there settle, pushing their beaks 

 through the outer tissue of the leaf or twig and feeding upon the 

 sap. Even in this early stage the male insect can be distin- 

 guished from the female by certain differences in structure. As 



