We are conducting a laboratory experiment on Orius survival after exposure to insecticide residues, and we would like to ensure we are releasing a good mix of male and female adults. Is there away to determine the sex through visual inspection while sorting live specimens?
It depends on your experimental set up, including how many individuals you need to sex, how quickly, how accurately, and how much handling can be done. The most reliable and accurate method is looking for presence/absence of an ovipositor. If that level of accuracy isn't required, relative body size and shape is pretty good, with females generally being larger and more 'robust' than males. If you're working with orius from Central/south Florida, it's worth verifying which species you have.
Adding to the perfect feedback from Stuart, based on my previous experience during my master studies, the abdominal terminalia is a key characteristic to differentiate between males and females in Orius spp. and most Anthocorid in general. Please see the attached print screen from my Master thesis.