6 BULLETIN 424, U. S. DEPARTMENT OF AGRICULTUEE. 



Table I. — Record of damage by the cottonwood borer (Plectrodera scalator) to 

 10 trees at Garden City, Kans., 1913. 





Tree No.— 



Total. 





1 



2 



3 



4 



5 



6 



7 



8 



9 



10 



Eg£;s 



2 

 9 

 

 2 





 5 

 1 

 2 







4 

 2 



1 





 6 



1 

 2 





 10 

 

 







7 

 

 





 14 

 

 2 







8 

 



8 





 6 

 

 2 





 9 

 

 1 



2 



Small larva3 



78 

 4 



Tunnels 



20 



The total of the eggs and small larvae was 80, an average of 8 to a 

 tree. Such a number of young larvae, nearly all of which were 

 working in the bark, would seriously check the growth of the tree, 

 as well as render the tree liable to damage by heavy winds. 



PREVENTIVE. 



Since the eggs are placed only on the trunks of the trees at 

 the surface of the ground, infestation is easily prevented by a screen 



cone about a foot 

 high, wrapped about 

 the base of the 

 tree and with its 

 lower edge sunk in 

 the ground. This 

 cone should fit the 

 tree trunk closely at 

 its top to exclude the 

 beetles and be set out 

 at the base an inch 

 or two to prevent the 

 eggs from being de- 

 posited through it. 

 It can be made by 

 cutting common win- 

 dow screen, usually 

 galvanized netting, 

 one-fourth to one- 

 half inch mesh, into 

 strips about 1 foot 

 wide and of the 

 proper length. Each strip is then slit from a third to half way 

 across from one edge at distances of from 3 to 4 inches, as shown 

 in the diagram (fig. 3). The screen is then wrapped around the 

 tree, the lap fastened at its lower end with a nail, pin fashion, and 



Fig. 3. — Diagram showing metliod of protecting trunk of 

 cottonwood against attack by the cottonwood borer. At 

 left, section of screen ; at right, cottonwood trunk show- 

 ing screen in position. Reduced. (Original.) 



