Polydrusus Weevils

Sarah Lisak, Brian Aukema, and Hailey Shanovich
Department of Entomology, University of Minnesota


The green immigrant leaf weevil (Polydrusus formosus) and the pale green weevil (Polydrusus impressifrons) belong to a group of beetles known as weevils or snout beetles.  There are 188 species of Polydrusus weevils, with four native to North America. These two species were introduced to North America from Europe in the early 1900’s and can now be found throughout much of North America. The pale green weevil is found to exist throughout the northern part of the US and southern Canada whereas the green immigrant weevil is only established in the northern half of the eastern US and into southeastern Canada. Both species are present in Minnesota. The adult weevils feed on the leaves and buds of a variety of hardwood and fruit trees, and occasionally on selected crops such as raspberry and strawberry (Table 1.) In Minnesota, both species can be found on ornamentals, urban trees, and occasionally on fruit crops (however, these weevils are not an economic concern).

Table 1. Trees and shrubs on which these two species have been found

Alder (Alnus)

Dogwood (Cornus)

Mountain Maple (Acer)

Red Maple (Acer)

American Hazel (Corylus)

Elm (Ulmus)

Oak (Quercus)

Strawberry (Fragaria)

Apple (Malus)

Hawthorn (Crataegus)

Pear (Pyrus)

Sugar Maple (Acer)

Aspen (Populus)

 Hazel (Corylus)

Pine (Pinus)

Thimbleberry (Rubus)

Basswood/Linden (Tilia)

Hop-hornbeam (Ostrya)

Plum (Prunus)

White Birch (Betula)

Beech (Fagus)

Ironwood (Olneya)

Poplar (Populus)

Willow (Salix)

Cherry (Prunus)

Leatherwood (Dirca)

Raspberry (Rubus)

Yellow Birch (Betula)


Figure 1.  Left: adult green immigrant leaf weevil (Polydrusus formosus), Right: adult pale green weevil (Polydrusus impressifrons) (Photo by Sarah Lisak)

Both weevils are known for their brilliant iridescent green scales that cover their bodies, though color vibrance and shade can range and color depends on lighting (Figure 1). Black patches may appear on weevils’ bodies where scales have been rubbed off from foraging in plants or handling.

Green Immigrant Leaf Weevil (Polydrusus formosus)

  • Color: reddish-green scales
  • Size: 0.2-0.27 in (5.3-6.8mm)
  • Body: narrow face, lined pattern on back

Pale Green Weevil (Polydrusus impressifrons):

  • Color: blueish-green scales
  • Size: 0.15-0.22 in (3.7-5.5mm)
  • Body: broad face, alternating line-dot pattern on back