36 



CIRCULAR 2 7 0, U. S. DEPARTMENT OF AGRICULTURE 



Pear Blight Beetle 



In the coastal area small, round holes, looking like shot holes, are 

 sometimes found in the trunks of apple and pear trees (the work of a 

 related species, the shot-hole borer (Scolytus rugulosus Katz.) is shown 

 in fig. 44). These are made by a small, blackish beetle, the pear 

 blight beetle, also known as the larger shot-hole borer (Anisandrus 

 pyri Peck). Trees are not attacked unless they are in an unhealthy 

 condition, which may have been brought about by mechanical or 

 winter injury, too much water, drought, insects, fungous diseases, or 

 some other cause. Any condition that may result in souring of the sap 



will attract the borers. The 

 beetles bore into the sap wood and 

 make tunnels through it in which 

 they lay eggs. The souring sap 

 favors the growth of a fungus, 

 and the young grubs feed on this 

 fungus and not at all on the 

 wood. In the fall the grubs 

 transform to beetles, which re- 

 main in the tunnels until spring, 

 when they emerge and construct 

 fresh tunnels. If the tunnels are 

 numerous, the growth of the 

 trees may be affected seriously. 



In order to prevent attacks of 

 this beetle, the trees should be 

 kept in a healthy, vigorous con- 

 dition ; and if they are unhealthy, 

 the cause should be determined 

 and corrected if possible. A 

 wash for slightly infested trees or 

 limbs, consisting of y 2 pint of crude carbolic acid, 1 gallon of fish-oil 

 soap or other soap, and 3 gallons of water, has been recommended by 

 the Oregon Agricultural Experiment Station. This should be painted 

 carefully on the infested portions only. 



Figure 44. — Work of the shot-hole borer, 



Scolytus rugulosus. 



Bronze Apple Tree Weevil 



The bronze apple tree weevil (Magdalis aenescens Lee.) attacks 

 devitalized apple and prune trees, making several small holes in a 

 patch in the bark. These are egg punctures, and the grubs hatching 

 from the eggs feed beneath the bark, causing a sunken, discolored 

 area about the size of a silver dollar. The adult beetles, which are 

 small, bronzy or black, and have snouts, emerge the following spring. 

 Attacks of this weevil may be prevented and controlled in the manner 

 described for the pear blight beetle. 



Flower Thrips 



Irregular whitish patches with dark centers very frequently appear 

 on the skin of apples (fig. 45). These have been called "pansy 

 spots," because they often resemble pansies in shape. They are most 

 noticeable on immature apples, and there may be 25 or 30 of them on 



