54 GRASSHOPPERS AND OTHER INJURIOUS INSECTS OF 1911 AND 1912. 



the field from infested seed harvested the year before. This would 

 not be the case, however, when seed has been kept more than one 

 year and is not so likely to occur when seed is drilled in. 



For co-operation and kindly assistance, acknowledgements are 

 due Mr. Herman Lentz of Wadena, Mr. Carl Billings of Audubon, 

 Wm. Tvohy and Martin Sweeney of Chatfield, Christ. Schultz of 

 Simpson, Joseph Jackson of Verndale. Our thanks are also due 

 Messrs. Craig, Hostetter, Eva, LeBorious, and Ryan of Du- 

 luth, and Messrs. Reynolds, Burk, Schroeder and Anderson of 

 Bemidji. 



SOME SHADE TREE TESTS. 



In the Thirteenth Report of the State Entomologist, issued in 

 December, 1910, five injurious shade tree and timber pests were 

 discussed, namely, Maple Borers, Elm Borers, Birch Leaf Skeleton- 

 izer. Box Elder Twig Borer and Larch Saw Fly. 



Since that was written the mortality amongst our shade trees 

 has markedly increased. This we believe has been due, in part, to 

 the excessive dryness during the summers of 1910 and 1911, so 

 weakening many of our oaks and other trees that they have suc- 

 cumbed to insect pests and various diseases much more readily than 

 they otherwise would. A somewhat alarming feature of the trouble, 

 however, is found in the fact that there has been found upon the 

 dead oaks a disease somewhat akin to the Chestnut Tree Blight 

 which is causing the death of valuable Chestnut trees in eastern 

 states. It must be seen then that the passing of our oaks is due not 

 entirely to the work of insects. Insect pests, however, play an im- 

 portant and possibly the most important part in the majority of 

 cases, and in October of the present year, Mr. Ruggles, Assistant 

 Entomologist, was asked to prepare a circular dealing with the 

 more important shade tree insects. This he has done, the publi- 

 cation being issued from this office as Circular No. 25, It deals with 

 the Two-lined Chetsnut Borer, probably the most important insect 

 enemy of Minnesota oaks, the Bronze Birch Borer, the Elm Borer, 

 (the two last were also discussed in the 13th Report), the Common 

 Flat-headed Borer, Rustic Borer, affecting oaks, and the Thunder- 

 bolt Beetle, We reproduce the circular here in full. 



Insect borers kill many Minnesota trees especially the oaks. 

 Dead trees or entire groves left standing imperil living trees. The 

 borers in the dead trees change into beetles much as the caterpillar 

 does into a butterfly or a moth. The beetles fly to healthy trees 



