The two-spotted spider mite is a common pest in horticulture and to control these mites greenhouses often use chemical pesticides or another type of mite, Phytoseiulus persimilis, which preys on this pest. This small-scale project found proteomic differences between virgin and mated female P. persimilis which, with further development, could lead to a simple test for industry to assess the reproductive capacities of commercially produced predatory mites. Despite the promising proof-of-principle results from this project, the relatively high cost to industry of developing a test further makes it unlikely at the current time that a commercial test will result from this project.