About Hypera nigrirostris (J.C.Fabricius, 1775)
Hypera nigrirostris, commonly known as the lesser clover leaf weevil, grows to a length of about 3 to 4 mm (0.12 to 0.16 in). Its rostrum, or beak, is three times as long as it is broad, and is notched at its base. The weevil's eyes are large, transverse, and non-protuberant. The frons is narrower than the rostrum, while the pronotum is broad. The proximal ends of the elytra have parallel sides and bear prominent humeral humps. The general body color of the insect is black, with a reddish tinge to its legs and antennae. The pronotum has a greenish-gold sheen, and the elytra have a greenish metallic appearance; both of these features come from the presence of dissected scales.
In northeastern Saskatchewan, adult lesser clover leaf weevils overwinter in red clover fields. The insects become active in late April, and eggs are laid between early May and mid-July inside clover shoots, leaves, and stipules. Developing larvae go through four instars and feed on clover stipules, buds, and inflorescences. Pupation takes place between late June and August, either on the clover plants or on the ground beneath them. When the new generation of adults begins to emerge in late July, the density of the weevil population increases sharply. In Canada, this species is often parasitized by other insects and by an entomopathogenic fungus, which help keep its population numbers under control.
