Ninth Report of the State Entomologist 369 



TJsually one spot only appears, but in one example three are seen. 

 They were accompanied with the following note: 



I send you by this mail, plum leaves covered with plant-lice, also 

 some plums that are affected from some cause. The trees from which 

 these plums were taken have been sprayed with strong soapsuds. ^ What 

 can be used to spray the trees that will kill the lice and not injure the 

 tree and its fruit ? " They are becoming very thick, not only on plums, 

 but also on cherry and peach trees. 



Mr. Smith was answered that the plant-louse infesting his plum trees, 

 was the plum-tree aphis, Aphis pruni Fabr. Their multiplication 

 could have been kept down by throwing a strong soapsuds or tobacco 

 water upon them, if it had been done earlier and before they had com- 

 menced to acquire wings. A kerosene emulsion of a moderate strength 

 would have been still better. But unfortunately it is quite difficult ta 

 reach the insects, gathered as they are on the underside of the 

 leaves, where they feed. They could best be reached by a 

 Yermorel nozzle attached to the end of a rod, and throwing an 

 upward fine spray. This species so seldom appears in destructive 

 numbers that the above report of its presence is rather a surprise. It 

 is probable that its numbers will show a diminution soon, although 

 it continues on the plum throughout the season, not migrating to 

 another food-plant, as do some other species, as notably the hop-vine 

 aphis, Phorodon hmnuU — its associate during the early spring. 



The affected fruit has been attacked by the fungus known as the 

 ^' brown rot," Monilia fructigena Pers. For this, spraying with a cop- 

 per solution would perhaps be the best that can be done, but it is not 

 probable that it would be of much benefit at this time when the fungus 

 has made so great progress. It should have been done, as a preventive,, 

 before the leaves expanded in the spring, and at intervals thereafter. 



The cherry aphis {3fyzus cerasi) reported, is still more difficult to 

 reach. The kerosene emulsion should have been used upon it on its 

 first appearance, before it had multiplied to the extent of sheltering 

 its myriads within the curled leaves which accompany its attack, where 

 they are virtually inaccessible. 



The peach-tree aphis, Myzus persicce (Sulzer), although curling the 

 foliage to a certain extent, may be more easily reached by the kerosene 

 emulsion than the preceding species. Destructive pests as are most of 

 the plant-lice, and of prodigious powers of multiplication, they are by 

 no means beyond control if operations are commenced against them 

 soon after their first appearance, or if proper sprays are applied to the 

 plants or trees that they infest while the foliage is absent, to kill their 



eggs. 



1893 47 



