APHIDS INJURIOUS TO OECHARD FRUITS. 



27 



death of dormant-budded nursery trees (fig. 20) and do serious or 

 fatal injury to young orchard trees. In mild climates the insects 

 may exist all winter on the twigs, reproducing during periods of 

 warmth, though the twigs are for the most part reinfested each year 

 from the insects below the soil. 



The complaints of serious injury by this species on the roots of 

 orchard peach trees, in the experience of the writers, have not been 

 justified, the un- 

 thrifty condition 

 of the trees being 

 in most cases due 

 to other causes. 



SEASONAL HISTORY. 



The complete 

 seasonal history 

 of this species is 

 not known. The 

 number of 3^oung 

 produced by a 

 given parent va- 

 ries greatly, de- 

 pending upon 

 weather c o n d i - 

 tions. Sometimes 

 only one young 

 aphis a day will 

 be produced, with 

 a total of 25 or 

 30 young to a 



mother, while under favorable conditions as many as 12 young may 

 be produced in a day and considerably over 100 as the total for a 

 given parent. In spring large numbers of winged forms appear and 

 the percentage of these gradually increases until all of the forms 

 above ground have become winged. These fly to some plant or plants 

 not known and are not met on peach foliage until the next year. 



CURRANT AND GOOSEBERRY APHIDS. 



THE CURRANT APHIS.' 



The currant aphis is distributed over the entire country and its 

 injury, on account of its conspicuousness, is the occasion of much 

 complaint. The insect causes the terminal leaves to become much 



Fig. 20. — The black peach aphis : Injury to dormant-budded 

 peach nursery stock in the spring. (Original.) 



^Myzus ribis (L.). 



