Sandy pitfall traps are an elaborate construction to capture prey and antlions are well-known representatives of this predation technique. From a soil mechanical perspective, antlions exploit the interactions between the particles of their habitat and engineer a stable trap. This construction is close to the unstable state, where a prey item will immediately slide towards the center - towards the ambushing antlion - when accidently entering the trap. This method is efficient, but requires permanent pit maintaining. According to the present knowledge, antlions throw sand at their prey, to distract it, and/or cause sand slides towards the center of the pit. Using sand throwing and escape experiments, as well as finite element analysis, we supported this hypothesis. Furthermore, we added new hypothesis about maintaining the pitfall trap. We showed that sand that accumulates in the center of the pit will be continuously removed, which lead to the slope maintenance close to an unstable condition. This avoids self-burial of the antlion, as well as decreasing the chance of prey item escapes by keeping the slope angle steep. This demonstrates the interaction of an insect larva with its abiotic environment from a novel perspective and adds further insights into longstanding entomological hypotheses.

中文翻译：

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从土壤力学的角度看沙坑建造蚁巢幼虫的投掷

沙坑陷阱是捕获猎物的精心构造，而蚂蚁是这种捕食技术的著名代表。从土壤力学的角度来看，蚂蚁利用其栖息地颗粒之间的相互作用并设计了一个稳定的陷阱。这种构造接近不稳定的状态，当意外进入陷阱时，猎物会立即向中心滑动-向伏击的小蚁滑动。该方法是有效的，但是需要永久性的凹坑维护。根据目前的知识，蚂蚁向它们的猎物扔沙子，以分散它们的注意力，和/或使沙子滑向坑的中心。使用抛沙和逃生实验以及有限元分析，我们支持了这一假设。此外，我们添加了有关维护陷阱陷阱的新假设。我们表明，积聚在坑中心的沙子将被连续清除，从而导致边坡维护接近不稳定状态。这样可以避免自行埋葬蚂蚁，并通过保持倾斜角度陡峭来减少猎物逃逸的机会。这从新颖的角度证明了昆虫幼虫与其非生物环境的相互作用，并为长期的昆虫学假设提供了进一步的见解。