210 Forty- fifth Report on the State Museum. 



Preventives of Hop-vine Aphis Attack. 



There are at least three methods by which much may be done to 

 prevent attack: 



1. Cut down and burn all the. wild plum trees in localities where 

 hops are grown, so as to afford fewer places where the hop-vine aphis may 

 oviposit in the autumn. Include in this such cultivated plum trees as 

 are not yielding paying crops, particularly if infested with black-knot. 



2. Spray all cultivated plum trees with a strong kerosene emulsion 

 during the winter, or in' the early spring before the leaves are out, in 

 order to destroy the eggs of the hop-vine aphis which may have been 

 deposited there the preceding autumn. The kerosene should penetrate 

 and quickly kill all the eggs which it reaches.* 



3. Collect and burn all the refuse (leaves and vines) of the hop-yard 

 as soon as the crop is picked. At this time many of the male aphides, 

 which are the last to leave the yard, are still upon the vines, and in the 

 burning, it is believed, that their number may be reduced to the extent 

 that enough will not remain to fertilize all the . females that have 

 already taken their departure. The mating occurs largely, if not 

 wholly, upon the plum trees. 



The above directions involve watchfulness and labor, but the demand 

 they make is trifling in comparison with the value of the crop that may 

 thereby be rescued from destruction. 



The figures in the above are from the Entomological Division of the 

 U. S. Department of Agriculture, obtained through the kindness of 

 Dr. Riley. 



The Melon Aphis, Aphis cucumeris Forbes. 



Lowell, Mass., August 21th. 



Eds. Country Gentleman. — I send you by mail a box containing 

 some muskmelon leaves and shoots that have been attacked by what seems 

 to be a kind of plant-louse. Last season they destroyed my little plat 

 when the melons were half -grown, the vines appearing as if touched by 

 frost. Can you tell me what the creature is, and what means could be 

 used as a preventive ? I presume that it is too late now to save the 

 vines, though I did not notice any trouble until yesterday. — T. C. B. 



The aphides or plant-lice, from the fortnight's delay in reaching me, 

 had become shriveled and discolored, but there is scarcely a doubt that 

 they are the species which was described and named by Professor Forbes, 



* Late experiments have shown it to be doubtful if aphis eggs can uniformly be killed by- 

 spraying with the emulsion. It would certainly be effective if made to reach the young aphides 

 soon after their coming from the egg. 



