Gymnetron linariae
(Coleoptera : Curculionidae)
Root-galling Weevils

Photos:  Root Galls and Adult

Photo by C. Paete, CABI Biosciences

Origin:  The original source of this species is the Upper Rhine Valley (2).  The native distribution is Eurasia (2).

Life Cycle:
Overwintering State:  Gymnetron linariae overwinters as an adult (2).

Egg Stage:  The eggs are placed individually into chewed pockets in the root tissue.  The egg is then covered  by excrement.  Most of the eggs are laid in the root crown (1,2).

Larval Stage: In this stage the larvae grow on the roots in galls (swellings) (2).

Adult Stage:  The adults come out in the spring.  They begin laying eggs after about three weeks, after feeding on toadflax (1,2).

Plant species attacked:  The plant species attacked is the yellow toadflax and Dalmation toadflax (2).

Impact on Host:  The feeding on yellow toadflax and Dalmation toadflax is unknown.  It is thought that the gall growth may affect the toadflax root formation and reproduction capacity (1,2).

Destructive stages:  The destructive stages are the larval and adult stages (2).

Habitat:  Gymnetron linariae's habitats are grasslands, fields, pastures, and places infested with Dalmation or yellow toadflax (1).

Now established in:  Not released (2).

First introduced into the United States:  Gymnetron linaria has not been approved for release in the United States yet (2).

Availability:  Not available (2).

Transfer stage:  The transfer stage is the adult (1,2).

Redistribution:  Not yet determined (2).

Remarks:  This insects' impact on yellow and Dalmation toadflax has not yet been determined.  It is thought that the root galls may minimize the plant vigor by acting like a nutrient sink.


1.  Hansen, Rich, Gymnetron linariae [web site] Available: larinus_obtrusus.html, updated last, Sept.. 1, 1998.

2. Rees, Norman, et. al., Ed., Biological Control of Weeds in the West, Western Society of Weed  Science, in Cooperation with USDA ARS, MT Dept. of Ag, and MT State Univ., Color Printers, Bozeman, MT, Feb., 1996.

By:  Mikael Moore,  02/03.

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