Bug FAQThistle Crown Weevil
Trichosirocalus horridus · Order: Coleoptera · Family: Curculionidae
Also called: Musk thistle rosette weevil
The thistle crown weevil is a true weevil that originates from Europe. It was released in the United States in 1974 to control invasive thistles such as Cirsium and Carduus. Both adults and larvae feed on thistle rosettes, with the larvae causing the most plant damage.
Source: Wikipedia
How to recognize it
It is a species of true weevil.
Source: Wikipedia
Is it a pest in the house?
Its role is to control thistle weeds rather than to infest homes.
Source: Wikipedia
Where it lives
It was introduced to the U.S. as a biological control agent for exotic thistles.
Source: Wikipedia
What it eats
It feeds on the rosettes of thistles.
Source: Wikipedia
Life cycle
Larvae develop within thistle rosettes and cause most of the damage.
Source: Wikipedia
Where it comes from
The weevil is native to Europe.
Source: Wikipedia
Where it is found in the US
Recorded in 12 of 51 states and DC. Most records: Kansas, Tennessee, North Carolina, Colorado, Nebraska, West Virginia, Iowa, Kentucky.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: introduced in Canada. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
Why was it introduced to the United States?
It was released in 1974 as a biological control agent against invasive thistles.
Source: Wikipedia
Same family (Curculionidae)
Green Immigrant Leaf WeevilPolydrusus formosusDamages trees, gardens or crops
Black Vine WeevilOtiorhynchus sulcatusDamages trees, gardens or crops
Nettle weevilPhyllobius pomaceusDamages trees, gardens or crops
Asian Oak WeevilCyrtepistomus castaneusDamages trees, gardens or crops
Strawberry Root WeevilOtiorhynchus ovatusDamages trees, gardens or crops
Common Leaf WeevilPhyllobius pyriDamages trees, gardens or cropsSources
- Wikipedia: https://en.wikipedia.org/wiki/Trichosirocalus_horridus
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-28 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-28.