A brown and white butterfly resting on bare ground
It was sitting on the bare ground of a trail in Medog, surrounded by scattered gravel and dry twigs, not a flower in sight. The wings were brown and white, marked with bold black stripes and clean white spots, and it stayed put while I crouched down for a closer look. Some butterflies vanish the moment you approach. This one seemed happy to pose.
This is Hestinalis nama, known in English as the Circe, a member of the brush-footed butterfly family Nymphalidae in the order Lepidoptera. The family name comes from the small, brush-like front legs that adults tuck against their bodies, which is also why they often look like they only have four legs walking around. The Circe is a butterfly of wooded lowlands across much of Asia, and Medog, tucked against the Himalayas in southeastern Tibet, sits right at the edge of its range.
That day the butterfly was doing what most adults do in between flower visits: warming up, resting, and watching the world from a patch of dirt. Its pattern of black stripes and white spots against brown is classic Nymphalidae camouflage, breaking up the outline so a perched butterfly reads as a bit of bark or a dead leaf rather than a meal.
As for the name Circe, it comes from the enchantress of Greek mythology, a fitting label for a butterfly that seems to hold anyone who watches it still. The species name nama is a quiet one, but the common name carries all the drama.
一直好奇蛱蝶那对退化的前足，收在胸前除了看起来像只用四条腿走路，是不是还保留了嗅觉或味觉之类的感知功能？文中提到它们停歇时在晒太阳、观察四周，那前足在这个过程中会起作用吗？
那对退化的前足不是摆设。它们虽然不参与走路，但上面布满感觉毛，主要承担化学感受功能——雌蝶靠它”尝”叶片，判断这是不是合适的产卵寄主；部分类群里雄蝶的前足还参与信息素或求偶相关的行为。所以”只用四条腿走路”只是外观描述，前足的功能被保留了下来，只是从支撑换成了感知。
晒太阳和警戒的时候，前足更多是收在胸前，那条通道主要靠复眼完成；把它理解成一对常驻的化学探头更贴切。