GRAPE PElSTS 7 



About the time that the grape buds begin to swell and break open, usually May 

 10-15, the larva leaves the eggshell and enters an opening bud to feed. Feeding 

 by the larva and the construction of its nest are most conspicuous during the last 

 week in May and the first week in June. The caterpillar becomes full grown and 

 begins to pupate about June 15 and the first moths appear about June 20, just 

 before the grape blossoms open. Moth activity reaches its peak about July 1, 

 and in the insectary practically all eggs have been laid and the moths have died 

 by July 10. Incubation of the egg begins soon after it is deposited, and the young 

 larva is developed in the egg by late July. 



NATURE OF INJURY 



Injury to grapevines by the grape plume moth is caused entirely by the larva 

 or caterpillar. When first hatched, the larva enters the swelling bud and feeds 

 slightly on the developing leaves. Occasionally this feeding injures or destroys 

 an embr>o flower bud. 



As the larva grows, it fastens together the terminal leaves of the shoot with a 

 web and feeds on the leaves in the shelter thus formed. In a few cases a blossom 

 cluster enclosed in the nest is injured but usually the feeding is confined to the 

 skeletonizing of the upper surface of the webbed leaves with an occasional hole 

 being eaten in them. 



As the cane grows, many of the webbed terminal leaves are torn and deformed 

 as they break away from the web. Since the feeding by the larva is usually fin- 

 ished about the middle of June, the injury is only slightly noticeable by July and 

 can scarcely be recognized by fall when the grapes are ripening. 



The grape plume moth causes little actual loss of fruit and its injury is most 

 annoying to home gardeners who take pride in the appearance of their grapevines. 



CONTROL 



Historical 



In 1896 J. B. Smith in New Jersey (13) stated: "Practically there is no method 

 of checking their increase, except by picking off the infested tips or crushing the 

 caterpillars within the webbed leaves." Surface m 191 1 (14), Britton in 1914 (2), 

 Quaintance in 1921 (10), and Slingerland and Crosby in 1922 (12), all recommend- 

 ed hand-picking of the caterpillars as the only method for keeping the insect in 

 check, especially on home plantings. 



Surface (14) suggests "spray with any arsenite while pests are young"; and 

 in 1933 Pettit (9) wrote: "... it is usually kept in check by the sprays used to 

 control the grapeberry moth ... It is best controlled by a spray of arsenate of 

 lead applied just before blossoming time ..." These are the only references to 

 control with insecticides until 1940, when the writers (15) reported on the use of 

 dormant sprays. 



In recent years in eastern Massachusetts, great interest in the control of this 

 insect has developed. Possibly this is due to heavier infestations or to greater 

 interest in grapevines as ornamental plants about the home. 



Natural Enemies 



Insect parasites were not an important factor in keeping the grape plume moth 

 under control in the vicinity of Waltham during the years when observations 



