Why Can Termites Fly During the Rainy Season? The Microscopic Secret Hidden on Their Wings

The flight of winged reproductive termites, known as alates, marks a critical moment in the life of a colony. At a particular season, mature alates leave their original nest, fly to new locations, find mates, and attempt to establish new colonies. Many termites choose to undertake this risky journey during the rainy season or shortly after rainfall. The reason is practical: rain softens the soil, making it easier for newly landed alates to dig into the ground and begin life in a new nest. Yet the rainy season also brings another challenge. For small insects with thin, lightweight wings, water droplets can disrupt flight, add extra weight, and even damage the wing surface. If termites are to fly in the rain, their wings must shed water droplets quickly enough to avoid being dragged down by the rain.

Mass flight of winged reproductive termites（Image source：Roshan Gracious， CC BY-SA 4.0 ）

A recent study approached this question by examining the fine surface structures of termite wings under the microscope. The researchers used differential interference contrast microscopy and scanning electron microscopy to observe termite specimens from the Natural History Museum in London. The samples covered both higher termites and lower termites, including 54 species from 16 families or subfamilies. Higher termites refer to termites belonging to the family Termitidae, while all termites outside this family are classified as lower termites. The distinction is mainly associated with differences in diet, digestion, gut structure, and symbiotic relationships. In this study, termite wings were examined as functional surfaces: did they possess setae? Did they have star-shaped micrasters? Were these structures arranged into regular arrays? The answers help explain how different termite species are adapted to flight in the rain.

A clear difference was found between higher and lower termites. The wing surfaces of higher termites often possessed micron-sized setae arrays, along with star-shaped micrasters distributed between the setae. Together, the setae and micrasters form a hierarchical structure. The larger setae can support larger water droplets, while the smaller star-shaped micrasters reduce contact between tiny droplets and the wing surface, allowing raindrops to be shed more easily during flight. These star-shaped structures usually consist of five to six arms and measure about 5 to 8 micrometers across. Scattered across the wing surface, they look like miniature stars. When water droplets touch the wing, these structures help keep the droplets supported, somewhat like the surface of a lotus leaf, preventing them from rapidly spreading into a thin film of water. Several termite groups examined in the study, including Microcerotermes, Nasutitermes, and Spinitermes, possessed this type of structure.

Wing setae and star-shaped micrasters in different higher termite species,（A）Microcerotermes zuluensis；（B）Microcerotermes parvus；（C）Euchilotermes tensus；（D）Cephalotermes rectangularis；（E）Nasutitermes novarumhebridarum；（F）Nasutitermes arborum；（G）Nasutitermes banksi；（H）Nasutitermes costalis；（I）Spinitermes trispinosus；（J）Termes hospes；（K）Termitogeton planus；（L）Microcerotermes turneri（Image source：Shen Y et al. (2026)， CC BY 4.0 ）

3D structure of star-shaped micrasters（Image source：Shen Y et al. (2026)， CC BY 4.0 ）

Lower termites showed a different pattern. In most lower termites, the wing surface was smoother and lacked arrays of setae and star-shaped micrasters. Instead, only nanoscale curved projections could be observed. Species assigned to this type in the study included Reticulitermes, Schedorhinotermes, Zootermopsis, Mastotermes, and several species of Kalotermitidae. These wings are more easily wetted by water, suggesting that they are more likely associated with nighttime flight under drier conditions. In other words, different termite groups appear to rely on different conditions for their colonization flights.

Wing surfaces of lower termite species, (A)Schedorhinotermes holmgreni）; (B) Mastotermes darwiniensis; (C) Bicornitermes bicornis; (D) Hodotermes mossambicus（Image source：Shen Y et al. (2026)， CC BY 4.0 ）

The study also recorded species that did not fit neatly into these two main categories. For example, Eutermellus convergens and Sphaerotermes sphaerothorax lacked star-shaped micrasters but possessed a double-layered setae structure composed of long and short setae. This shows that anti-wetting adaptations do not follow a single design. Other species, such as Macrotermes michaelseni, Tuberculitermes guineensis, Coptotermes acinaciformis, and Postelectrotermes militaris, had a setae array but no star-shaped micraster array. These termites were inferred to be better suited to flight in dry conditions.

Double-layered setae in (A) Eutermellus convergens and (B) Sphaerotermes sphaerothorax（Image source：Shen Y et al. (2026)， CC BY 4.0 ）

Single-layered setae in (A) Tuberculitermes guineensis, (B) Macrotermes michaelseni, (C) Coptotermes acinaciformis, and (D) Postelectrotermes militaris（Image source：Shen Y et al. (2026)， CC BY 4.0 ）

Termite wings also lead us into the broader world of biological materials. Insects often use micro- and nanoscale structures on their body surfaces to regulate water, contamination, light, and friction. Butterfly wings, cicada wings, the leg setae of semi-aquatic insects, and the cuticular hairs that allow some insects to retain thin layers of air all show that biological surfaces are finely tuned functional interfaces. In higher termites, tiny setae and star-shaped micrasters take part in a minute but consequential evolutionary change, helping connect rainy-season flight, predator avoidance, suitable soil conditions, and the founding of new colonies.

Author: Shui-Ye You

Reference:

Shen Y et al. (2026). Microstructural Analysis of Termite Wings: Implications for Hydrophobic Adaptations in Rainy Flight. Insects.