FRUIT CULTURE. 43 



haps wanting in plant food, that there are insects upon those 

 spots. The mealy aphis is almost always found upon those 

 spots. If Professor Fernald is here, he can probably 

 give us the history of that insect and tell us of the 

 remedy. 



Mr. Ckuikshank. I would say that we have l)een in- 

 formed that an insect is the cause of it, ))ut we have not 

 been able as yet to find anything of an insect nature to 

 which to attribute it. The only remedy we could find was 

 to amputate the limb. The question is, what is the cause 

 and what the remedy, otherwise than that? 



Prof. Fernald. I do not know the insect at all. It 

 does not hail from where I came from. There are many 

 varieties of the aphis. I do not know the one to which 

 reference is made. That must be a Massachusetts insect. 



Mr. A. W. Cheever of Dedham. I would like to ask 

 Prof. ]Maynard if this mealy aphis cannot be properly called 

 the cotton aphis? 



Prof. INIaynard. Yes, sir. It has a white cottony sub- 

 stance on its body. 



Prof. Ferxald. We have a long list of names which 

 might be applied to them, because their number is legion. 

 I do not think I would harbor plant lice of any kind. 

 Whether they are able to carry contagious diseases from one 

 place to another is an open question. This raises the whole 

 question of what is the cause of the yellows, pear blight, and 

 so on. If they are contagious diseases, the question is 

 whether these plant lice may not transport the disease to 

 other trees ? That is a queston of great interest. So I would 

 not harbor plant lice at all. 



Question. Whether or not, over-bearing is one of the 

 prominent causes of pear blight ? 



Prof. Maynard. Not necessarily ; and j^et anything that 

 weakens the growth of the tree renders it liable to the at- 

 tacks of these fungoid growths. It is undoubtedly a growth 

 similar to those. Fermentation sets in and the plant is not 

 vigorous enough to overcome it. The spores are every- 

 where present ; but pear blight always, or almost always, 

 implies some weakness in the tree. 



Mr. Myrick. What do you do for the apple maggot ? 



