It is unlikely that any insects would have been brought in through the Dr. Earth Home Grown Potting Soil. It is comprised of organic materials which are treated to remove insects and disease before packaging. You may browse products we sell for spider mite control here.
Dr. Earth Home Grown Organic Potting Soil is a 1.5 cubic feet bag so the amount of area that 1.5 cubic feet of soil will cover depends on the depth of the soil layer and the project. To calculate cubic feet, you can multiply the length x width x depth of the 10 ft x 14 ft area.
NOTE: This product has been discontinued. Please see Natural & Organic Soil Amendments for Lawn & Garden for similar products