Sweetclover weevil

Sitona cylindricollis

The adult feeds on the foliage of legumes, especially yellow sweetclover (Melilotus officinalis) and lucerne in spring and autumn. Crescent-shaped pieces are eaten out of the leaves. When infestation is severe, entire leaves except for the midrib may be consumed, and the outer surface of stems damaged (Anon., 1981). 
The larvae feed on the root hairs and nodules in summer (Bird, 1947). However, Manglitz et al. (1963) showed that damage to the nodules by S. cylindricollis and S. hispidula larvae is of two types. The young first-instar larvae burrow into the nodules without leaving any external signs. When the contents are devoured and only the cortex remains, the larva exits through small holes. The other type of nodule damage is caused by feeding of older larvae. If plants of sweetclover are dug up, the root nodules will be found to contain small, legless larvae.
Sweetclover seedlings which were infested only with larvae of S. cylindricollis were reduced in size (Manglitz et al., 1963).

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