Social insects face threats to the colony during the day but also at nighttime. Multiple strategies have evolved across social insect species that protect the nest and each other at night. We asked what behaviors are employed by stingless bees, Tetragonisca angustula at night. We describe two layers of defense, nightly nest closing and night guarding at the entrance. After monitoring 10 naturally occurring colonies, we saw considerable variation in the likelihood of colonies leaving a nest open or closing them at night. Furthermore, more guards were at the entrances of open nests than closed nests. The mass of nightly guarding bees and tube closers was consistent with (even slightly exceeding) the mass of daytime guards, suggesting that these tasks are performed by especially large soldier bees. We found preliminary evidence supporting the hypothesis that the kairomone citral, released by obligate kleptoparasites, encourages nest closing behavior. Two nests that were consecutively open for a week, partially closed the night we applied alarm pheromone. These data are just a glimpse into some of the nightly defensive behaviors and what shapes nest closure behavior. We discuss how these data are an important first step and discuss hypotheses emerging from this study.

群居昆虫在白天和夜间都面临着对群体的威胁。在夜间保护巢穴和彼此的社会昆虫物种之间已经发展出多种策略。我们询问了无刺蜜蜂Tetragonisca angustula 的行为在晚上。我们描述了两层防御，夜间关闭巢穴和在入口处夜间守卫。在监测了 10 个自然发生的菌落后，我们发现菌落在夜间打开或关闭巢穴的可能性有很大差异。此外，开放巢穴入口处的守卫比封闭巢穴多。夜间守卫和管子闭合器的数量与白天守卫的数量一致（甚至略超过），表明这些任务是由特别大的兵蜂执行的。我们发现了支持以下假设的初步证据，即由专性盗链寄生虫释放的 kairomone 柠檬醛会促进巢穴关闭行为。两个连续开放一周的巢穴，在我们应用警报信息素的那天晚上部分关闭。这些数据只是对一些夜间防御行为以及巢穴关闭行为的影响的一瞥。我们讨论这些数据如何成为重要的第一步，并讨论本研究中出现的假设。