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SOME INSECT PESTS OF CULTIVATED BLUEBERRIES 



William E. Tomlinson, Jr. 

 Cranberry Station, East Wareham 



The different insects that are kno^^m to infest cultivated blueber- 

 ries are quite numerous, but fortunately only a few are of enough impor- 

 tance to require the use of pesticides. The important ones in Massachu- 

 setts have been cranberry weevil, cranberry fruitworm, cherry fruitworm, 

 blueberry maggot, and Japanese beetle. Several others are occasionally 

 troublesome. 



Much future trouble from a few insects can be avoided by proper 

 pruning. Stem galls should be removed and disposed of in such a manner 

 that the gall -producing wasps they contain cannot emerge from the galls 

 and infest new twig growth in the spring. The galls preferably should 

 be burned, or at least buried under several inches of soil. Canes in- 

 fested with stem borers should be removed whenever noticed, regardless 

 of the time of year, but during the pruning operation is an excellent 

 time to be on the watch for signs of their activity. Orange -colored 

 frass pellets under an infested cane indicate an active borer. Be sure 

 to remove the cane below where it is tunnelled and probe for any tunnels 

 in the crown with a twig or wire if they have worked that far down in 

 the bush. Though not an entirely reliable scale insect control, regular 

 removal of older, less productive canes low in the crown, is helpful in 

 retarding the development of serious scale insect infestations. When 

 scales do become abundant, a thorough spraying with superior oil in the 

 dormant season is a dependable control. 



On quiet, warm, sunny days in the spring, after the fruit buds swell 

 but before bloom has opened, is the time to be on the alert for cranberry 

 weevil, especially on bushes around the edges of the field. An occasion- 

 al one can be ignored, but if they occur several to the bush, the field 

 should be treated. The weevils lay eggs in the unopened blossoms and 

 the developing larvae feed on the flower parts, one larva per blossom. 

 Because of their small size and earliness in the season, they may go un- 

 detected for several seasons, with the result that they build up to out- 

 break numbers, and the small crops that result may be attributed to some 

 other cause, such as frost or lack of pollination. 



After the blossoms have set, the small green fruit is siibject to the 

 attack of several different species of insect larvae. Two are of very 

 little importance, though they account for a few less fruit almost every 

 season. The grub of the plum curculio'is the first of these, its pres- 

 ence being indicated by a crescent-shaped scar on the berry. A few are 

 noted almost every year in Massachusetts , but in North Carolina this is 

 a major blueberry pest. 



Another minor pest is the maggot of a small fly that develops in the 

 green fruit. At picking time these appear as ripe berries, except for a 

 small green circular area on one side of a berry that hasn't ripened nor- 

 mally due to the feeding and secretions of the maggot of this midge. A 



