Phratora polaris is a species of leaf beetle found in the Nordic regions of Europe.,[1][2][3] occasionally in Scotland,[4] and Iceland.

[11] In most of its range, P. polaris adults and larvae feed and lay eggs on willow (Salix) plants.

[10] Male[1] and female genitalia of P. polaris (which can be observed with live beetles under the dissecting scope when pressure is applied to the abdomen), closely resemble those of P.

Mitochondrial sequences at the mitochondrial cytochrome c oxidase subunit I (DNA barcoding) gene show more divergence among willow- vs birch-feeding populations of P. polaris within Finland than between willow-feeding populations of P. polaris from Finland and P. tibialis from Switzerland.

[11] Like other Phratora species at high altitudes and latitudes, P. polaris probably undergoes one generation within a growing season.

[20] Using host plant compounds to make the larval defensive secretions appears to be the evolutionarily advanced or derived state of this trait.