Hypera nigrirostris

(Fabricius, 1775)

lesser clover leaf weevil, black-beaked green weevil

Hypera nigrirostris, commonly known as the lesser clover , is a small to Europe and northern Africa that has been to North America and Japan. It is a specialized of leguminous plants, particularly red clover (Trifolium pratense), and has become a significant agricultural pest in red clover seed production systems where larval feeding can reduce yields by up to 50%.

Hypera nigrirostris by (c) Owen Strickland, some rights reserved (CC BY), uploaded by Owen Strickland. Used under a CC-BY license.

Hypera nigrirostris, Dyffryn, North Wales, June 2010 (18127417110) by Janet Graham. Used under a CC BY 2.0 license.

The Coleoptera of the British islands. A descriptive account of the families, genera, and species indigenous to Great Britain and Ireland, with notes as to localities, habitats, etc (1891) (14756056746) by Internet Archive Book Images. Used under a No restrictions license.

Pronunciation

How to pronounce Hypera nigrirostris: /haɪˈpɛɹə nɪɡˌrɪˈrɒstrɪs/

These audio files are automatically generated. While they are not always 100% accurate, they are a good starting point.

Identification

Distinguished from similar Hypera by the combination of: length-to-width ratio of 3:1 with notch; greenish metallic and sheen from dissected ; small size (3–4 mm); and black body with reddish appendages. The prominent humps on the elytra and the relatively broad pronotum compared to width are additional diagnostic characters. In agricultural settings, presence in red clover fields during the growing season provides ecological context.

Images

Habitat

Agricultural and semi-natural dominated by Fabaceae, particularly red clover (Trifolium pratense) fields. overwinter within red clover fields in temperate regions. The requires environments supporting its plants through the growing season, from spring through late summer .

Distribution

to Europe and northern Africa; and established in North America and Japan. Within North America, documented in agricultural regions of Canada (northeastern Saskatchewan) and the United States, with presence in all lower 48 states inferred from agricultural pest records. GBIF records confirm presence in Belgium and North America.

Seasonality

become active in late April to early May following . occurs from early May through mid-July. Larval development spans early June to mid-August, with four . from late June to August. New- adults emerge from mid-July, causing sharp increases. Seasonal activity is tightly coupled to red clover .

Diet

on Fabaceae. Primary are red clover (Trifolium pratense), clover (T. repens), and alsike clover (T. hybridum). Secondary hosts include pea, alfalfa, and vetch. chew holes in leaves and create hollows in stems. feed on stipules, , and , with each larva damaging three to four flower during development.

Host Associations

Trifolium pratense - primary red clover; main in agricultural systems
Trifolium repens - primary clover
Trifolium hybridum - primary alsike clover
Pisum sativum - secondary pea
Medicago sativa - secondary alfalfa
Vicia - secondary vetch

Life Cycle

emerge in late April–early May and immediately begin feeding, mating, and . are laid subepidermally in stipules, shoots, and leaves from early May to mid-July. hatch and develop through four while feeding on stipules, , and , present from early June to mid-August. occurs on stems or in ground debris from late June through August. New adults emerge from mid-July, with increasing sharply. Spatial distribution of eggs and larvae is aggregated, becoming less clumped as larvae develop.

Behavior

exhibit aggregated spatial distribution patterns for , with and young clustered on plants. Adults are capable of in situ within host fields rather than dispersing to protected sites. New- adults show synchronized in mid-July, creating detectable surges. Larvae are relatively sedentary, remaining on the same plant or through development.

Ecological Role

and agricultural pest in legume cropping systems. In its range, likely functions as a regulator of wild clover . In regions, has become a significant economic pest of red clover seed production. in Canada has been observed through and , though these are insufficient for economic management in agricultural settings.

Human Relevance

Major pest of red clover seed production in North America, with documented yield losses up to 50% from larval feeding. and have been developed for in red clover seed systems. Management strategies include early harvest, grazing, - , chemical control (with safety concerns), and through . Prophylactic use has been common due to lack of established thresholds, creating risks of resistance development and pollinator harm.

Similar Taxa

Hypera postica; larger with different rostral proportions and coloration, primarily attacks alfalfa rather than clover, and has a more western North distribution
Other Hypera speciesDistinguished by the unique combination of proportions (3:1 length:width with notch), greenish metallic coloration, and specific associations with Trifolium

More Details

Economic Impact

The first data-driven for North red clover seed systems were established in 2024, providing foundation for cost-effective, -conscious management strategies.

Taxonomic Note

Originally described as Apion nigripes; current combination in Hypera reflects revised generic placement within .