78 



AMERICAN FORESTRY 



THE GYPSY MOTH PARASITE 



These two wagonloads are an importation of gypsy-moth caterpillars from France 

 in 1909, en route to the laboratory at Melrose Highlands, Massachusetts. These 

 caterpillars were brought into this country for the purpose of introducing 

 beneficial parasites to assist in controlling the gypsy moth. 



many important diseases of plants which have not \'et 

 gained foothold on this continent. Prominent among 

 these are the mildew diseases of the Indian com occurring 

 in the Orient; the potato wart, and many others affecting 

 cultivated plants and forest trees. 



Dangers From New Regions 



The increasing commerce of the world with the hither- 

 to little explored regions of China and other Asiatic coun- 

 tries and Africa, Oceania, etc., adds enormously to the 



risk of the importation of new pests. We know very little 

 of ihc injurious insects of these new countries, but the 

 importation of new stock in the last few years from these 

 regions by the Department of Agriculture and by private 

 agencies has especially demonstrated the existence therein 

 of man\' very dangerous plant pests. The importance of 

 these may be illustrated by referring again to some im- 

 portant pests now established in this country from these 

 hitherto little explored regions of the old world. In this 

 list comes the San Jos^ scale, the chestnut blight, citrus 

 canker, and the com mildews, introduced into some of 

 our Southern States. 



Excluding the Pests 



The more important of these known foreign pests are 

 being excluded bj' regulating the entry of nursery stock, 

 or, in the case of diseases, by an absolute prohibition of 



ADULT MALE HESSIAN FLY (MAYETIOLA DESTRUCTOR) 



When excessively abundant this insect either destroys or badly injures hundreds 

 of thousands of acres of wheat, reducinR the yield from 50 to 75 per cent. This 

 pest alone probably causes an annual loss in the United States of fifty millions 

 of dollars. 



THE FLUTED SCALE (ICERVA PURCHASI MASK) 



Introduced from Australia and at one time threatened the entire citrus industry 

 of the Pacific Coast. Fortunately, through the introduction and establishment 

 of its natural ladybird enemy, Novius cardinalis, this pest is now under control, 

 resulting in the annual saving of hundreds of thousands of dollars to the citrus 

 growers. 



the entry of the plants or fruits affected. There are now 

 in force nine foreign plant quarantines forbidding the en- 

 try into the United States of various plants and plant 

 products to prevent the entry of new and dangerous 

 pests. Two of these have relation to forest pests, 

 namely the white pine blister rust and the European 

 pine shoot moth. The others relate to the potato wart; 

 the Mexican fruit fly; the pink boll womi of cotton; 

 the avocado weevil; certain injurious insects and fungous 

 diseases of the sugar cane ; citi-us canker and other dan- 

 gerous citrus diseases; and the downy mildews and P/ij/- 

 soderma diseases of Indian com. 



