Bug FAQBrown Argus
Aricia agestis · Order: Lepidoptera · Family: Lycaenidae
The Brown Argus butterfly has brown upper wings with a band of orange spots and a grey-brown underside with black spots outlined in white and orange border spots. It lives across the Palearctic, from northern Denmark to Siberia, and is common in many habitats such as fields, chalk downlands, woodland clearings and gardens. Caterpillars feed mainly on common rock-rose on calcareous soils, but also on dove's-foot cranesbill and common stork's-bill in other areas.
Source: Wikipedia
How to recognize it
Both sexes have brown upper wings with a row of orange spots along the wing edges. The underside shows a grey-brown ground colour with black spots edged in white and a line of orange spots at the border.
Source: Wikipedia
Where it lives
They fly low over fields, paths, rocky hills and gardens, and are among the most common butterflies. They are frequent on chalk downlands, but also use woodland clearings, coastal grasslands and heathland.
Source: Wikipedia
What it eats
Larvae prefer common rock-rose on calcareous soils. In other habitats they also feed on dove's-foot cranesbill, common stork's-bill and possibly other Geranium species.
Source: Wikipedia
Life cycle
Eggs are pale green, flattened, with a concave top and a finely netted surface. In the south there are two generations per year, flying in May-June and again from late July to mid-September; further north they have one generation in June-July.
Source: Wikipedia
Lookalikes
It can be confused with other female blues, but unlike them it never has blue scales at the wing base.
Source: Wikipedia
Where it is found in the US
Recorded in 2 of 51 states and DC. Most records: Colorado, Pennsylvania.
Darker = more records. Counts are museum and citizen-science records, not population size.
Source: GBIF
More photos
Questions people ask
How can I tell a Brown Argus from other female blues?
Look for the absence of blue scales at the wing base; Brown Argus lacks them.
Source: Wikipedia
When are Brown Argus butterflies active?
They fly in May and again from July onward, with two generations in the south and one in the north.
Source: Wikipedia
What plants do Brown Argus caterpillars eat?
They mainly feed on common rock-rose, and also on dove's-foot cranesbill and common stork's-bill.
Source: Wikipedia
Where is the Brown Argus found?
It is widespread across the Palearctic, from northern Denmark to Siberia and the Tian Shan.
Source: Wikipedia
Same family (Lycaenidae)
Sources
- Wikipedia: https://en.wikipedia.org/wiki/Aricia_agestis
Look it up elsewhere: GBIF · iNaturalist · BugGuide · Wikipedia
Text written 2026-10-24 from the sources above and checked sentence by sentence against them. Data fetched 2026-10-22.