Queen-laid eggs are positioned at the bottom of the cell. Immediately after oviposition the egg is almost perpendicular to the cell wall. It is sometimes suggested that the egg sags gradually during its development until it rests on the bottom of the cell [1]. However, some eggs do not change position before hatching [2]. In absence of workers position of the egg is independent of its age and its sagging is caused by workers pushing the egg with head during incubation [3]. (scale bar = 1 mm)

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