Many insects are unable to fly after being drenched in rain, but butterflies can maintain flight.

In the natural world, many bird feathers possess a certain waterproof effect due to the well-developed uropygial gland of birds, which can secrete oil to achieve waterproofing. Unlike birds, however, butterflies employ "nanotechnology" in their wings.

Under a microscope, it's observed that the surface of butterfly wings is covered with numerous tiny scales. These scales are not randomly arranged but are neatly stacked and overlapped on the wing membrane in the same manner as tiles on a roof, forming a waterproof barrier. Moreover, there are tiny gaps between these scales. When raindrops form on the surface of butterfly wings, these gaps help the droplets gather, causing them to slide off.

When the scales are magnified, it's discovered that their surface is not smooth; rather, it's rough, resembling gears with fine raised lines. These raised lines, akin to teeth on gears, have a diameter even smaller than a hair strand, belonging to the nanometer scale.

The scales are not randomly attached to the wings but grow on them like leaves. Rows of scales are neatly stacked and arranged, covering the entire wing in a consistent sequence, similar to tiles on a roof. When raindrops fall on the scales, the teeth, finer than a needle, break the raindrops into many small droplets, significantly reducing the impact force of rainwater on the butterfly wings and minimizing the contact area between the wings and rainwater.

Simultaneously, this structure forms a guiding slope, allowing the water droplets to quickly roll along the gaps between the scales to the edge of the wings. Therefore, when raindrops hit the butterfly, they merely brush past it, without wetting the butterfly.

In the natural world, the most familiar waterproof material is the lotus leaf. Raindrops falling on lotus leaves only roll around, forming a large water droplet, yet they cannot wet the lotus leaf. The characteristic of lotus leaves not absorbing water is similar to the innate ability of butterflies not to get wet. There are also nanoscale pillars on the surface of lotus leaves.

Rainwater only falls on the top of these pillars, greatly reducing the contact area between water droplets and the leaf surface. However, as waterproof materials, butterflies are more robust than lotus leaves.

However, if encountering prolonged heavy rainstorms, the tiny butterflies still cannot resist the force of nature. They will seek shelter from the rain and fold their wings to protect themselves from the invasion of rainwater. The nanoscale scales on butterfly wings can produce a dispersing repulsion effect on water droplets. Scientists have utilized this principle to develop superhydrophobic coatings.

The current high manufacturing cost and complex process limit their large-scale production and application. If these issues regarding manufacturing cost and preparation process are resolved, this type of superhydrophobic coating will broaden its applications in various fields, bringing great convenience to humanity.