Bug FAQAlligatorweed Thrips
Amynothrips andersoni · Order: Thysanoptera · Family: Phlaeothripidae
Also called: Fungus-feeding thrips
Adult Alligatorweed Thrips are shiny black insects about two millimeters long, while the larvae change from tan to bright scarlet red as they grow. Both larvae and adults feed on alligator weed leaves, causing leaf curling and stunting, and the species has been released in the southeastern United States to help control this invasive plant.
Source: Wikipedia
How to recognize it
Adults are shiny black and about two millimeters long. First-instar larvae are tan, and second-instar larvae turn bright scarlet red.
Source: Wikipedia
Size
An adult measures roughly two millimeters in length.
Source: Wikipedia
Is it a pest in the house?
It was imported and released in the United States specifically to feed on alligator weed.
Source: Wikipedia
How to get rid of it
The species is used as a biological control agent against the invasive aquatic plant known as alligator weed.
Source: Wikipedia
Where it lives
The thrips is now established across much of the southeastern United States.
Source: Wikipedia
What it eats
Both larvae and adults feed on alligator weed, especially leaf buds and edges, which leads to leaf curling and plant stunting.
Source: Wikipedia
Life cycle
A female lays about two hundred eggs during her ninety-day adult life. Mated females produce both male and female offspring, while unmated females produce only males.
Source: Wikipedia
Where it comes from
It originates from South America.
Source: Wikipedia
Where it is found in the US
Recorded in 3 of 51 states and DC. Most records: Mississippi, Louisiana, North Carolina.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
What does Alligatorweed Thrips look like?
Adults are shiny black and about two millimeters long; larvae start tan and turn bright scarlet red in later stages.
Source: Wikipedia
Where is Alligatorweed Thrips found?
It is native to South America and now established throughout much of the southeastern United States.
Source: Wikipedia
How does this thrips affect alligator weed?
Both larvae and adults feed on leaf buds and edges, causing the leaves to curl and the plant to become stunted.
Source: Wikipedia
Why was Alligatorweed Thrips introduced to the U.S.?
It was released as a biological control agent to help suppress the invasive alligator weed.
Source: Wikipedia
Same family (Phlaeothripidae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Amynothrips_andersoni
Look it up elsewhere: GBIF · iNaturalist · BugGuide · ITIS · Wikipedia
Text written 2026-10-23 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-23.