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Further vernacular names:

Clover Root Curculio

Classification:

Sitona hispidulus belongs to the subfamily Entiminae, tribe Sitonini.

Distribution:

Europe, Asia, adventive in North America.

Habitat:

Fields, pastures, meadows, wasteland, roadsides, also at higher altitudes - in places where clover grows.

Description:

Length 3.5 - 4.5 mm; upper side with scales and hairs; elytra broader than the pronotum, with long projecting bristles, brown spotted; scutellum with scales directed to the rear; pronotum widely coarsely punctured, with paler, narrower middle and wider lateral stripes; forehead flat, with eyelashes; eyes very weakly arched; femora not toothed; claws not intergrown at base.

Biology:

The Clover Weevil Sitona hispidulus is a common and widespread species that lives on plants of the pea family (Fabaceae). The weevils prefer wild growing and cultivated Trifolium- and Medicago species.
From mid-summer onwards, the adults of the new generation appear. They feed on foliage leaving distictive notches on leaf margins of the host plants. About 6 to 8 weeks after hatching, the females begin to lay their eggs. The eggs are laid in late autumn and the following spring. The imagines and the eggs laid in autumn overwinter. The larvae hatch from April and feed on the roots of their host plants until they pupate. The pupal stage lasts 3 - 4 weeks.
Sitona hispidulus forms one generation per year. The adult beetles are long-lived. Their lifespan is about 1 year.

Natural enemies:

Entomophagous nematodes: Steinernema feltiae, Steinernema bibionis and Heterorhabditis bacteriophora - Nematodes parasitize larvae, pupae and adult beetles.
Microctonus aethiopoides (Hymenoptera: Braconidae) - This species parasitizes adult weevils. It lays an egg into the abdomen of the beetle. After hatching the Microctonus aethiopoides larva feeds and develops inside the beetle.
Anaphes diana (Hymenoptera: Chalcidoidea: Mymaridae) - The fairy wasp Anaphes diana is an egg parasitoid of Sitona species.

References, further reading, links:

1. Yunakov N. (2017). 3i Curculio: 3i taxonomic databases, Curculionidae, subfamily Entiminae (version Jan 2017). In: Species 2000 & ITIS Catalogue of Life, 2017 Annual Checklist (Roskov Y., Abucay L., Orrell T., Nicolson D., Bailly N., Kirk P.M., Bourgoin T., DeWalt R.E., Decock W., De Wever A., Nieukerken E. van, Zarucchi J., Penev L., eds.). Digital resource at www.catalogueoflife.org/annual-checklist/2017. Species 2000: Naturalis, Leiden, the Netherlands. ISSN 2405-884X.
2. Arved Lompe: Die Käfer Europas - Ein Bestimmungswerk im Internet
3. Kaitlin Rim, Steven J Price, Erik J Wenninger, Rachael Long, Ricardo A Ramirez: Biology and Management of Clover Root Curculio (Coleoptera: Curculionidae), Journal of Integrated Pest Management, Volume 10, Issue 1, 2019, 23, https://doi.org/10.1093/jipm/pmz020