the colony is lacking a queen. Myrmecia workers are highly fertile and can successfully mate with males. A colony of M. pyriformis without a queen was collected in 1998 and kept in captivity, during which time the gamergates produced viable workers for three years. Ovarian dissections showed that three workers of this colony mated with males and produced female workers. Queens have bigger ovaries than the workers, with 44 ovarioles while workers have 8 to 14. Spermatheca is present in M. gulosa workers, based on eight dissected individuals showing a spermatheca structurally similar to those found in queens. These spermathecas did not have any sperm. Why the queen was not replaced is still unknown. Vision While most ants have poor eyesight, Myrmecia ants have excellent vision. This trait is important to them, since Myrmecia primarily relies on visual cues for navigation. These ants are capable of discriminating the distance and size of objects moving nearly a metre away. Winged alates are only active during the day, as they can see better. Members of a colony have different eye structures due to each individual fulfilling different tasks, and nocturnal species have larger ommatidia in comparison to those that are active during the day. Facet lenses also vary in size; for example, the diurnal species M. croslandi has a smaller lens in comparison to M. nigriceps and M. pyriformis which have larger lenses. Myrmecia ants have three photoreceptors that can see UV light, meaning they are capable of seeing colours that humans cannot. Their vision is said to be better than some mammals, such as cats, dogs or wallabies. Despite their excellent vision, worker ants of this genus find it difficult to find their nests at night, due to the difficulty of finding the landmarks they use to navigate. They are thus more likely to return to their nests the following morning, walking slowly with long pauses. Sting Myrmecia workers and queens possess a sting described as "sharp in pain with no burning." The pain may last for several minutes. In the Starr sting pain scale, a scale which compares the overall pain of hymenopteran stings on a four-point scale, Myrmecia stings were ranked from 2–3 in pain, described as "painful" or "sharply and seriously painful". Unlike in honeybees, the sting lacks barbs, and so the stinger is not left in the area the ant has stung, allowing the ants to sting