To effectively combat Wraiths either Capacitors will need to be employed or X-Ray Scanner technology will need to be Researched so regular Turrets can target the ghosts as well. Both methods have their drawbacks:
- Capacitors require manual intervention and the translucent nature of Wraiths and necessity to multi-task means their threat can be forgotten easily.
- X-Ray Scanner technology reduces the overall range of your turrets (passively and permanently) meaning it cancels the benefit of Optics. Also, Wraith are pretty resistant to non-AP bullets and explosives ; see the X-Ray Scanner for details.
Apart from their invisibility, they are pretty weak overall. Don't underestimate their threat, they are clearly here to distract you from the more subtantial menaces. To combat them still requires reaserch from your R&D team in either case, unless you want to rely on your buildings shields instead.