38 



USEFUL BIRDS. 



by insects, and have estimated in each case the probable average yearly 

 reduction in value caused by these pests. The data used are given be- 

 low. I have tried to make a conservative estimate in the case of each 

 product, since, to have any value, such an estimate should fall below 

 rather than above the actual amount. Even then the figures afford 

 material for serious reflection on the part of agriculturists. 



Assuming the accuracy of these data, and exclusive of the damage 

 wrought by insects to our woodlands, street trees, parks, etc., we have 

 in round figures five million dollars as the average annual damage from 

 insects to agricultural products and property in this Commonwealth. 



While the cost of insect injury is enormous, the expense 

 of fighting injurious insects in the attempt to protect crops 

 and trees from their ravages is proportionately great. In 

 recent years Massachusetts has had, and is still having, a 

 costly experience in attempting to control or suppress an 

 imported insect. 



The gipsy moth (Porthetria dispar), a well-known pest 

 of European countries, was introduced into Medford, Mass., 

 by Mr. Leopold Trouvelot, in 1868 or 1869. Twenty years 

 later the moths had increased in numbers to such an extent 

 that they were destroying the trees and shrubbery in that 

 section of Medford where they were first liberated. 



They swarmed over the houses of the inhabitants, invaded 

 their gardens, and became such a public nuisance that in 

 1890 the Legislature appropriated fifty thousand dollars for 

 their extermination. It w r as learned within the next two years 

 that the moths had spread over thirty towns. The State 



