How do you know when a wolf spider is adult or mature?

As with (most!) spiders, Ricardo, they display fully adult sexual morphology. In male wolf spiders (Lycosidae), this takes the form of enlarged distal (end) segments to their pedipalps (like little boxing gloves just in front of the mouth: http://www.spiders.us/files/spider-geni … oscope.jpg) and for the female, she has a fully formed epigynum (http://www.spiders.us/files/female-spiders-epigynum.jpg). These act, partly, as 'lock-and-key' mechanisms to prevent / reduce cross-breeding.

Obviously, a number of spiders are sufficiently closely related to produce viable hybrid offspring but in the main, these physical characteristics (plus other behavioural cues) prevent too much cross-breeding: http://www.bioone.org/doi/abs/10.1111/j … 07.00146.x