314 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



hoped that parasites or other natural enemies can be introduced and 

 estalilished in New Jersey. One sending from Japan of a predatory 

 beetle has already been received. 



Peach insect investigations. — Investigations of })each insects 

 have been continued in Georgia, Mississippi, and Arkansas. Peach 

 growers in Georgia last year suffered very heavy losses from the 

 combined injuries of the plum curculio and brown-rot. which were 

 notably more prevalent than in previous years. During the growing 

 season of 1920, the curculio has been even more destructive, causing a 

 heavy loss estimated conservatively at about $2,000,000 for the State. 

 Unusual weather conditions and other factors have so increased the 

 abundance of this pest that treatments effective in its control during 

 normal times were quite ineffective under the conditions which pre- 

 vailed. There is some evidence that in the presence of abundant rains 

 and high temperatures the curculio may develop a partial second 

 brood of larva) which infest the ripening fruit, causing an increased 

 proportion of wormy fruit at harvest time. The inconspicuous char- 

 acter of the curculio egg punctures on the peach makes it difficult to 

 detect infested fruit, and undesirable quantities may be gathered and 

 shipped to the market in spite of the best efforts of the growers. The 

 importance of the situation warrants a careful reinvestigation of the 

 whole subject of curculio control in peach orchards in the South. 



The work in INIississippi has been continued under more favorable 

 conditions and the data obtained confirm previous conclusions that 

 under average weather conditions dusting of trees with insecticides 

 and fungicides is as effective in the control of the curculio as spray- 

 ing. Large-scale experiments have been undertaken with arsenicals 

 in the post-harvest treatment to destroy the curculio during the 

 period over which they are supposed to be feeding in orchards and 

 iDefore they enter hibernation. The curculio population in treated 

 and untreated blocks is ascertained by systematic jarring operations, 

 taking records of the beetles caught. 



Further experience with para-dichlorobenzene as a treatment for 

 the peach borer indicates the effectiveness and safety of this treat- 

 ment for this very serious pest. The use of this material is now being 

 adopted by numerous orchardists, and no failures have been reported. 

 In Arkansas an orchard of about 200 acres was treated last fall with 

 para-dichlorobenzene, and large purchases of the chemical have been 

 made for use in Georgia and other peach-growing districts during 

 the fall of 1920. 



Apple insect investigations. — Codling moth. — Life-history studies 

 of the codling moth have been continued about as described in the 

 last report, though work was undertaken in one new locality, namely, 

 northern Georgia, to ascertain the number of generations and other 

 life-history facts relative to the insect in this southern locality. The 

 work on the codling moth in Colorado has been completed, and re- 

 ports on life history and on experimental work in orchards are now 

 in the coui-se of publication. Information has been obtained on the 

 effect of low temperatures on the insect; thus the winter of 1919-20 

 in the Roirue River Valley was the coldest in the history of the local 

 station. This spring a large percentage of overwintering larvae was 

 found dead. The same experience was observed at Yakima, AVash. 



