42 



the fact that commonly only one beetle emerges from each cluster of egg cavities, as 

 proven by the single exit hole, indicates either that a largo proportion of the eggs or 

 larvae are destroyed or else that but few eggs are laid. Probably both explanations 

 are true in part. 



In nearly all cases these egg cavities are burrowed iu or immediately adjoining 

 bark attacked by the "black spot" or canker, a fungous disease caused by Macro- 

 phoma mali Peck. In only a few instances did we observe egg burrows in healthy 

 bark, and in these cases the trees were much weakened by the attacks of the fungus. 

 We were quite unable after a careful search to find any trees unaffected by the 

 canker that were attacked by the weevil, and there can be no doubt that the dam- 

 age caused by the weevil is very insignificant compared to that caused by the 

 fungus. As the tissue invaded by the fungus always dies within a year, it follows 

 that the weevil does no dainnge in such spots; and as it attacks healthy bark so 

 seldom it certainly does but little injury. It is possible, however, that if the canker 

 is held in check the beetles may attack healthy bark more frequently. 



Feeding habits of the adult. — Our earliest record of the appearance of the adult is 

 April 15. From this time on, as late at least as the middle of August, the beetles are 

 abundant. Shortly after their first appearance they may be found laying eggs, and 

 as new adults are constantly emerging, this goes on through the whole season. The 

 adults are found only occasionally on the trunks of the trees, usually where they 

 are ovipositing or have just emerged. On the leaves of the trees, however, they are 

 abundant, and are frequently found in coitu. They feed only on the pulp of the leaf, 

 biting out shallow holes usually to the lower epidermis of the leaf but sometimes 

 quite through. Where very abundant many of the leaves come to be quite riddled 

 from their attacks, though ordinarily this injury is of slight consequence. The 

 beetles are not very quick nor easily alarmed, so that their actions may be watched 

 indefinitely, even with the use of a lens. 



The species evidently single brooded. — From the egg to the adult occupies apparently 

 one year. This would seem clearly to be the case from the relations of the insect 

 and the canker disease. The canker spots begin in the fall and reach their limit of 

 growth, which is sharply marked, either before or early in the next spring. In this 

 diseased tissue the eggs of the weevil are laid during the summer. By the follow- 

 ing summer the cankered bark is dead and nearly dry, and covered with the black 

 spore containing pustules. It is always from bark of this kind that the adult 

 beetles emerge. We have never found them in older dead and diseased bark, which 

 indeed separates from the wood at this time, and only rarely does the larva burrow 

 beyond the limits of the diseased tissue. It necessarily follows that the larval and 

 pupal stages do not occupy more than one year, and from the same facts they can 

 require little less time than that period. 



FURTHER INVESTIGATION DESIRABLE. 



The desirability of additional observations and investigations becomes 

 obvious to anyone who has perused the preceding paragraphs. It seems 

 not impossible, in the absence of positive proof to the contrary, that 

 certain canker-like spots or blotches on apple trees may in reality be 

 caused primarily by the attack of the borer and that parasitic fungous 

 attack is secondary. Professor Piper, however, writes that canker 

 spots are common without the presence of larvae and that young- 

 canker spots seldom show any egg punctures. 



It is also possible, and even probable, that more than one fungus is 

 present in limbs affected by the weevil, and further study will be neces- 

 sary to establish the economic status of all the factors that contribute 

 to the premature demise of the trees in the affected region. 



