Imported longhorned weevil: Injury and damage

Imported longhorned weevil injury: Imported longhorned weevil, Calomycterus setarius, injury to soybean leaves. 1 [left], 5 [center], and 15% [right] tissue removal is shown. Weevils make a distinct irregular pattern of leaf injury on soybean leaves as seen here.Imported longhorned weevil injury: Imported longhorned weevil, Calomycterus setarius, injury to soybean leaves. 1 [left], 5 [center], and 15% [right] tissue removal is shown. Weevils make a distinct irregular pattern of leaf injury on soybean leaves as seen here. (Photo Marlin E. Rice)

Imported longhorned weevils on soybean: Imported longhorned weevils, Calomycterus setarius, on soybean.Imported longhorned weevils on soybean: Imported longhorned weevils, Calomycterus setarius, on soybean.

Imported longhorned weevils have, on rare occasions, rare in Iowa; however, they have been reported here as long as 64 years ago (Rice and Pilcher). Originally imported from Japan in 1929, they can occasionally cause significant foliar injury in seedling to V4-stage soybean (Rice and Pilcher 1998, Hunt et al. 2003). Typically this insect is concentrated at the boarders of fields and moves inward as the population grows (Rice and Pilcher 1998). Injury has been reported from this pest in Iowa from late June to early July (Rice 1994).

Imported longhorned weevils have, on rare occasions, caused significant foliar injury in seedling to V4-stage soybean (Rice and Pilcher 1998, Hunt et al. 2003). Typically this insect is concentrated at the borders of fields and moves inward as the population defoliates rows along the field edge (Rice and Pilcher). However, even under extremely large populations, significant defoliation is confined to border rows as the soybean plants away from the field edge grow larger and faster than the advancing weevils can defoliate them. Injury has been reported from this pest in Iowa from late June to early July (Rice 1994). Plants that are completed defoliated may not produce any beans.