Spider mites are one of the most common and most hated foes of indoor and outdoor cultivators, these tiny pests are members of the Acari (mite) family Tetranychidae and have around 1,200 individual species.
Webs on the underside or on-top of fan leaves and flowers (sometimes completely covering plants) as well as specs from them sucking the juices from your plant and also tiny specs of black droppings.
Spider mites prefer an environment that is dry and hot but are most likely to attack a garden that is fluctuating from moist to dry and hot to cold, so the best thing you can do is keep a steady predictable environment that maintains around 75-80F 45% humidity. Neem oil can be sprayed up to a week into flower without causing residue in your buds and will drive most garden pests away from your crop!
Sulfur and sulfur burners can be used in your room before you put in your plants and even during early veg, this will coat the walls of the room with sulfur and make it very undesirable for a vast majority of insects as well as mold and mildew.
Once a spider mite infestation has become severe during flowering you will be very low on options so it is best to treat your plants as part of a IPM (integrated pest management) we always recommend neem and products like Azatrol for plants that are still in veg and up to a week into flower.