Adult weevils are elongate, up to 15 mm long and 5 mm wide. They are brownish when young, turning blacker with age. This is the only stage normally visible, as eggs are laid into holes bored into the stem. The large white larvae remain inside the stem and feed on plant tissue.
The stem-boring weevil was first released in Australia in 1993. This was followed up by an active redistribution process that lasted until 2000. The stem-borer is now distributed across the range of Onopordum thistles in eastern Australia.
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<table style="border:1px solid;padding:2px; width:310px;" ><tr><td><a href="https://www.scienceimage.csiro.au/image/3179/"><img src="https://www.scienceimage.csiro.au/images/embed/300_0_BE3695.jpg" width="300" alt="Thistle Stemborer Weevil, Lixus cardui" style="margin: 0 0 5px 0; border: 0px;"></a><br/><a href="https://www.scienceimage.csiro.au/image/3179/">Thistle Stemborer Weevil, Lixus cardui</a><br />by CSIRO</td></tr></table>
Thistle Stemborer Weevil, Lixus cardui