They are oval shaped, dark brown or black, and about 5–10 millimetres (3⁄16–3⁄8 in) long.

It feeds on floral buds, primarily of thistles, with the larvae stage being the most destructive to them.

Once hatched, the larva has a segmented white body with a brown head, and is C-shaped.

[1] Larinus planus prefers dryer ranges, but can also adapt to wetter locations.

tracyi, a sparsely distributed thistle native to western Colorado and eastern Utah.

Subsequent research determined that the weevil reduced seed production of the native thistle.