330 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 14 



Table I 



Totc.1 610 520 



Larval Activity. Upon hatching from the egg the young larva im- 

 mediatel}'- attempts to bore its way into the bark of the tree. If it suc- 

 ceeds, a tiny pile of frass marks the point of entrance. The young 

 larva spends a considerable part of its life tunneling in the corticular 

 region of the bark. During this period it may travel a considerable 

 distance, and it leaves behind a tortuous trail of darkened tissues just 

 beneath the surface of the outer bark. We cannot say what is the 

 length of time which the larva spends in this way, but we have found 

 in these superficial burrows larvae ranging from newly hatched to fif- 

 teen millimeters in length. 



Apparently upon reaching a length of fifteen or twenty millimeters 

 the larva proceeds to form its typical tunnel in the cambium beneath 

 the bark, which constitutes the characteristic injur}-' so well known to 

 peach and prune growers. These tunnels are linear in form, usually 

 fairly straight, and extend vertically with the grain of the wood; al- 

 though irregular, side tunnels are not infrequently found. We have 

 found tunnels of this type as small as thirty two by seven millimeters. 

 The complete tunnels usually vary in width from fifteen to thirty mil- 

 limeters or more, and extend vertically to a length of one hundred to 

 one hundred fifty millimeters or more. The most common location 

 of these tunnels is at the crown of the tree; the upper extremity of 

 the tunnel ordinarily extending some thirty millimeters above the 

 soil surface, the lower extremity reaching some distance below the 

 soil surface. We have frequently observed a round hole, approxi- 

 mately seven millimeters in diameter connecting the complete tunnel 

 with the exterior just at the surface 3f the soil. This opening is not 

 invariably present however, and many burrows are to be found without 

 any apparent communication with the exterior. 



The presence of larvae is not limited to the crown of the tree. Es 

 pecially on rough bark trees larvae may be found working on the trunk 

 and in the crotches. This species seems to show a greater tendency in 

 this respect than does the Peach Tree Borer of the East, Sanninoidea 

 exitiosa Say. 



