64 



CIRCULAR 2 7 0, U. S. DEPARTMENT OF AGRICULTURE 



and establish new infestations. The aerial forms usually disappear 

 by midsummer. 



CONTROL 



If the root form is numerous enough to affect the growth of the 

 trees, it should be controlled. This may be done with some effective- 

 ness by using paradichlorobenzene, as recommended for the peach 

 borer (p. 55). The aerial form may be controlled readily with the 

 usual nicotine sprays. 



Peach Twig Borer 



Ripening peaches are sometimes wormy, and this worminess may 

 be associated with a split pit. The brown worms in these peaches 

 are peach twig borers (Anarsia lineatella Zeller) , so 

 named because early in the spring the young 

 worms burrow into the tender terminal growth of 

 the trees and cause the rapidly growing twigs to 

 wilt (fig. 72). The injury is twofold: (1) The 

 development of the new growth is interfered with ; 

 and (2) there is a direct loss of fruit. The peach 

 twig borer also attacks prune and apricot trees, 

 and the twig injury is especially serious on nursery 

 trees or in young orchards. The species origi- 

 nated in Europe and has been in the United States 

 for many years. 



LIPE HISTORY 



The young peach twig borers pass the winter in 

 very small silk-lined burrows, known as hiber- 

 nacula, in the bark. These are usually con- 

 structed in the folded bark found in the crotches 

 of the younger branches. Each burrow has a 

 characteristic projecting tube or " chimney," com- 

 posed of silk and tiny pieces of bark, which is 

 difficult to see without a lens. The small worms 

 leave these winter quarters as soon as twig growth 

 has commenced and burrow into the new shoots, 

 where they feed on the pith and inner bark, thus 

 causing the shoot to wilt. Frequently a single 

 worm injures several twigs in this manner. 

 By May the worms are mature, nearly one-half of an inch long, and 

 reddish brown. They spin loose cocoons in rough places in the bark 

 or in curled leaves, and the small, inconspicuous, grayish moths emerge 

 in June. These lay minute eggs on the bark, and the tiny worms 

 hatching from them attack the fruit as well as the new growth. They 

 usually burrow into the peaches near the stem end and feed around 

 the pit; or if this is still soft, they enter it and feed on the kernel. 

 This second brood of worms also produces a brood of moths which lay 

 eggs, and the young woims hatching from these build the silken bur- 

 rows in which the winter is spent. 



Figure 72. — Injury 

 to peach shoot by 

 the peach twig 

 borer. 



CONTROL 



The peach twig borer is very easily controlled by an application of 

 lime-sulfur solution as used for the San Jose scale (p. 11). If 



