THE PLUM CURCULIO IN APPLES IN MASSACHUSETTS 



By W. D. Whitcomb, Assistant Research Professor of Entomology 



ORIGIN AND DISTRIBUTION 



The plum curculio^ is native to North America where it bred freely in 

 the fruit of wild plums and hawthorns before the introduction of cultivated 

 fruits. As early as 1736 it was reported as a serious pest of garden plums in 

 the vicinity of Philadelphia, and since then it has been the subject of many 

 reports under such names as cheny weevil, peach worm, little Turk, kerkelo, 

 and little joker, as well as plum curculio. It appears to have been much 

 more abundant and destructive along the Atlantic Coast, and although known 

 to be present in the Mississippi Valley was not reported in large nvimbers 

 until about 1850. Surveys in 1910 indicated that it had not become estab- 

 lished west of the 100th meridian, and Quaintance and Jenne (9)" suggest 

 that the western boundary of the humid area constitutes the barrier which 

 governs its spread. Southern Canada and the Gulf of Mexico are the lati- 

 tudinal limits. 



IMPORTANCE IN MASSACHUSETTS 



It is the imanimous opinion of those concerned with the fruit growing 

 industiy of Massachusetts that the plum curculio is the most injurious insect 

 pest of apples in the state. Many orchardists believe that it is increasing its 

 destructiveness each year in spite of their efforts to check it. 



In some neglected and poorly cared-for orchards, every fruit on the tree 

 at harvest has been damaged, with the greater part of the apples bearing the 

 scars of three or more punctures. Even in orchards where an average spray 

 schedule was followed, the proportion of blemished fruit frequently reached 

 30 per cent and occasionally 60 per cent. 



During these studies as many as 310 curculios have been collected from one 

 ten-year-old tree, and 3067 beetles have been taken from twenty-five such 

 trees in an unsprayed orchard during the period when the beetles were 

 entering the trees from hibernation. 



A pest survey of the harvest fruit in forty-five Massachusetts orchards in 

 1928 showed the plum curculio to be the cause of more injury to apples than 

 any other insect pest, the damage by it frequentty exceeding that of all other 

 insects combined. 



As a result of the heavy loss to fruit growers, studies of this insect were 

 begun in 1926 by the writer with headquarters at the Market Garden Field 

 Station in Waltham, and this bulletin reports the progress of this work 

 to date. 



FOOD PLANTS 



The fruit of the native wild plum is the natural food of the plum curculio, 

 but that of cultivated plums is equally or more desirable, and the apple is 

 also a very satisfactory host. The beetles attack practically all stone and 

 pomaceous fruits and where these are grown in large quantities in the 

 ' infested area the curculio is likely to become an important pest. This has 

 been the case in the peach orchards of Georgia (11) and North Carolina (8), 

 and the apple orchards of Connecticut (5) and Massachusetts. 



1 Conotrachdus nenuphar Herbst, Order Coleoptera, Sub-order Rhyncophora, Fam- 

 ily Curculionidae. 

 - Numbers in parentheses refer to Literature Cited on page 52. 



