CRANBERRY WEEVIL

 

The cranberry weevil (Anthonomus musculus Say) ranges from Ontario and New England south to Florida and west to the Rocky Mountains. It is commonly found on chokeberry or huckleberry in the wild, and can become a serious pest of commercial blueberries and cranberries in the Northeast (Lacroix 1926). The cranberry weevil occurs in North Carolina, but seldom in populations large enough to cause economic loss.

The adult weevil is a dark reddish-brown beetle about 3 mm (1/8 inch) long. The front part of the weevil's head is elongated into a slender, curved snout (proboscis) which is about one-third to one-half as long as the rest of the body. The larva is smooth, slender, and legless. It has a yellowish-white body and a brown head.

Illustrations:

  • Adult stage of the cranberry weevil.
  • Weevil injury to blueberry buds.

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    Life Cycle and Seasonal Distribution


    Adults overwinter under debris in wooded areas adjacent to blueberry plantings. When the blueberry buds begin to swell in late February or early March, adults leave their winter quarters and congregate on blueberries. Eggs are laid in unopened flowers as soon as soon as individual blossoms stand out separately in the cluster. Larvae hatch in 3 to 9 days and eat the floral parts. Infested blossoms soon fall to the ground; larvae complete their development and pupate within these detached blossoms (Doehlert and Tomlinson 1951). New adults begin to emerge toward the end of May, and are usually present in the fields during summer and fall. There is only one generation per year in the blueberries, but a few individuals may produce a second generation on late-fruiting species of blueberry or huckleberry in the woods (Marucci 1966).

     

    Symptoms and Damage


    Weevils begin damaging blueberry plants in early spring after adults emerge from hibernation and start feeding and laying eggs. They puncture both leaf and flower buds with their mouthparts: heavily damaged flower buds fail to open and injured leaf buds produce an abnormal cluster of dwarfed foliage. Larvae feeding within the buds cause the infested blossoms to turn purple, remain unopened, wither, and fall from the plant (Marucci 1966). Later in the growing season, the feeding of adult weevils causes numerous small, irregular holes in the leaves, usually within a brownish dead area on both sides of the midrib (Franklin 1948). Frequently this injury occurs within leaves tied or rolled by other insects which have abandoned the structure.

     

    Natural Enemies


    Lacroix (1926) reported that a parasitic wasp identified as Habrocytus sp. (Hymeoptera: Chalcidoidea) had been reared from adult cranberry weevils. This is apparently the only record of a natural enemy attacking this pest. There is no evidence of parasitization in North Carolina weevil populations.

     

    Scouting, Management, and Control


    Adult cranberry weevils may be collected from blueberry plants with a sweep net or by shaking the foliage onto a white ground cloth. North Carolina populations are usually very small (even in abandoned blueberry fields), and natural control factors appear to keep this insect well below damaging levels. If supplementary chemical control is necessary, a short-residual contact insecticide should be applied about a week before buds begin to open.

    References

  • Doehlert, C. A. and W. E. Tomlinson, Jr. 1951. Blossom weevil on cultivated blueberries. NJ Agr. Exp. Sta. Circ. #504 (revised).
  • Franklin, H. J. 1948. Cranberry insect in Massachusetts. Mass. Agr. Exp. Sta. Bull. #445. 64 pp.
  • Lacroix, D. S. 1926. The life history and control of the cranberry weevil, Anthonomus musculus Say (Coleoptera: Curculionidae). J. Econ. Entomol. 19: 819-829.
  • Marucci, P. E. 1966. Insects and their control. In: Eck, P. and N. Childers (eds.) Blueberry Culture. Rutgers Univ. Press, NJ. pp. 159-235.
    • Last updated: 31 July 1996
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