Bug FAQAlligatorweed Flea Beetle
Agasicles hygrophila · Order: Coleoptera · Family: Chrysomelidae
The adult alligatorweed flea beetle is about 5 mm long, black with yellow stripes on its wing covers. It lives only on alligator weed in the southeastern United States and feeds on the plant as both larvae and adults. Females lay roughly 1,000 tiny eggs over six weeks, and the beetle has been used successfully to control invasive alligator weed in the U.S. and New Zealand.
Source: Wikipedia
How to recognize it
Adults are black with yellow stripes on the elytra.
Source: Wikipedia
Size
Adults measure about 5 mm in length.
Source: Wikipedia
Is it a pest in the house?
Defoliation of alligator weed mats by the beetle kills the weed and clears infested waterways.
Source: Wikipedia
How to get rid of it
It has also been introduced for weed control in New Zealand.
Source: Wikipedia
What it eats
Females lay rows of tiny eggs on leaves; the yellow larvae hatch and eat the leaves. Adult beetles also feed on alligator weed leaves.
Source: Wikipedia
Life cycle
A female can lay about 1,000 eggs during her six-week adult life.
Source: Wikipedia
Where it comes from
It is native to South America.
Source: Wikipedia
Where it is found in the US
Recorded in 9 of 51 states and DC. Most records: Florida, Louisiana, Georgia, Texas, North Carolina, Mississippi, South Carolina, Alabama.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
Status: introduced in United States. Source: iNaturalist
Months it is reported in the US
Source: GBIF
More photos
Questions people ask
What does the alligatorweed flea beetle look like?
Adults are about 5 mm long, black with yellow stripes on their wing covers.
Source: Wikipedia
Where can I find this beetle?
It lives on alligator weed in the southeastern United States.
Source: Wikipedia
How many eggs does a female lay?
A female lays about 1,000 eggs over her six-week lifespan.
Source: Wikipedia
Same family (Chrysomelidae)
Spotted Cucumber BeetleDiabrotica undecimpunctataDamages trees, gardens or crops
Bean WeevilAcanthoscelides obtectusDamages trees, gardens or crops
Cowpea WeevilCallosobruchus maculatusDamages trees, gardens or crops
Swamp Milkweed Leaf BeetleLabidomera clivicollisDamages trees, gardens or crops
Alder Leaf BeetleAgelastica alniDamages trees, gardens or crops
Dogbane Leaf BeetleChrysochus auratusSources
- Wikipedia: https://en.wikipedia.org/wiki/Agasicles_hygrophila
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 2026-10-22.