expanding on what Kruszakus was saying, the length of 'connection' time between the male and female does not necessarily mean more sperm is being deposited or increased female fertility. I'm not too familiar with mantids behavioural (reproductive) ecology and anatomy, but sperm transfer generally does not take long, however, when females are limited, males have to compete between each other for these limited resources. The best way to guarantee your paternity and your reproductive success is to guard your female from other males from mating with her, which is easily done by physically blocking the female's vulva by staying connected. The disadvantages of remaining connected to the female for too long includes 1) being eaten by the female 2) being eaten by a predator and 3) the male's 'reproductive success'/rewards from his investment decreases over time (diminishing returns). The other optimal male mating strategy is to spend less time mating (=less time in connection with the female) but mates with more females (i.e. Krus' and his Didymoryha).
