Bug FAQYellow-shouldered Stout Hover Fly
Simosyrphus grandicornis · Order: Diptera · Family: Syrphidae
The yellow-shouldered stout hoverfly is about ten mm long and has yellow edges on its thorax and yellow antennae. It is a common Australasian hoverfly that also occurs on many Polynesian islands and Hawaii. Its larvae develop near aphid colonies because they feed mainly on aphids.
Source: Wikipedia
How to recognize it
Yellow edges run along the sides of the thorax and the antennae are yellow. The species is named for its stout body shape.
Source: Wikipedia
Size
Adults are about ten millimetres long.
Source: Wikipedia
Where it lives
It has been introduced to several Polynesian islands and to Hawaii.
Source: Wikipedia
What it eats
Females lay eggs near aphid colonies because the larvae feed mainly on aphids.
Source: Wikipedia
Life cycle
Eggs are deposited close to aphid colonies to provide food for the developing larvae.
Source: Wikipedia
Where it comes from
Its native range is Australasia.
Source: Wikipedia
Where it is found in the US
Recorded in 1 of 51 states and DC. Most records: Hawaii.
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 do the larvae eat?
The larvae mainly eat aphids, so the flies are often found near aphid colonies.
Source: Wikipedia
Where is this hoverfly found?
It is common in Australia and has been introduced to many Polynesian islands and Hawaii.
Source: Wikipedia
How big is the yellow-shouldered stout hoverfly?
Adults are about ten millimetres long.
Source: Wikipedia
Same family (Syrphidae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Simosyrphus_grandicornis
Look it up elsewhere: GBIF · iNaturalist · BugGuide · Wikipedia
Text written 2026-10-22 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-22.