I agree. Spider mites usually start making the rounds in my roses & other shrubbery in late May, as temps get really hot. But you may hwant toconsider using a miticide instead of those products though, as our temperatures here in Texas preclude using hort oils now. With temps near or above 100F daily, I only got acceptable temps for hort oils from 6am until noonish. Instead, I have used Bayer Advanced 3-in-1Disease & Mite Control Concentrate, applied monthly, early in the mornings, on my roses/azaleas/camellias/hydrangeas with good results. Earlier in the season, when temps are cool, hort oils would be ok.
But tell me now, where did you get a camellia with flower buds at this time of the year???? Transplant shock zapped those buds. Here in Texas, camellias like evenly moist soil (no periods of dry soil then wet soil when you water and then dry soil). The heat present by being planted outside and the lesser humidity also did them in. Normally though, browning of the buds will happen during winter when we get drops into the teens or when we experience wild temperature swings of 50+ degress on a single day. For that, I recommend deep watering on the previous night and 2-4" of mulch all year around past the drip line. I have put mine so they get shade starting at around 11am... ish... in the summer months.