Division of Physical Science and Engineering, King Abdullah University of Science and Technology (KAUST), Thuwal, 23955-6900, Saudi Arabia.
Sci Rep. 2020 Oct 20;10(1):17829. doi: 10.1038/s41598-020-73583-2.
Drain flies, Pshycoda spp. (Order Diptera, Family Psychodidae), commonly reside in our homes, annoying us in our bathrooms, kitchens, and laundry rooms. They like to stay near drains where they lay their eggs and feed on microorganisms and liquid carbohydrates found in the slime that builds up over time. Though they generally behave very sedately, they react quite quickly when threatened with water. A squirt from the sink induces them to fly away, seemingly unaffected, and flushing the toilet with flies inside does not necessarily whisk them down. We find that drain flies' remarkable ability to evade such potentially lethal threats does not stem primarily from an evolved behavioral response, but rather from a unique hair covering with a hierarchical roughness. This covering, that has never been previously explored, imparts superhydrophobicity against large droplets and pools and antiwetting properties against micron-sized droplets and condensation. We examine how this hair covering equips them to take advantage of the relevant fluid dynamics and flee water threats in domestic and natural environments including: millimetric-sized droplets, mist, waves, and pools of water. Our findings elucidate drain flies' astounding ability to cope with a wide range of water threats and almost never get washed down the drain.
家蝇（双翅目，摇蚊科）常栖息于家中，在浴室、厨房和洗衣房骚扰我们。它们喜欢待在靠近排水口的地方，在那里产卵，并以随时间积累的污垢中的微生物和液体碳水化合物为食。虽然它们通常表现得非常温顺，但当受到水的威胁时，它们的反应非常迅速。从水槽中喷出的水会促使它们飞走，看起来没有受到影响，而将马桶内的苍蝇冲下去并不一定会将它们冲走。我们发现，家蝇逃避这种潜在致命威胁的非凡能力并非主要源自进化而来的行为反应，而是源自一种独特的毛发覆盖物，具有分层的粗糙度。这种从未被探索过的覆盖物赋予了它们超疏水性，可以抵抗大液滴和液池，同时具有抗湿性，可以抵抗微米级液滴和冷凝。我们研究了这种毛发覆盖物如何使它们能够利用相关的流体动力学，在家庭和自然环境中逃避水的威胁，包括：毫米大小的液滴、雾气、波浪和水洼。我们的研究结果阐明了家蝇应对各种水威胁的惊人能力，它们几乎从不被冲进下水道。
