We are not aware of any issues with using a bifenthrin product on St Augustine. This active is known for being super gentle on plants, so it should not harm it when used as directed on the product label.
There is not an expiration date printed on the Bifen IT bottle. This product will last for 3-5 years from the date of purchase if kept sealed and stored at room temperature.
Bifen IT will kill termites that come in contact with the chemical. To eradicate termites you want to use a product that has a transfer effect. Termidor SC is a great product to use to treat termites. Please see our Termite Control Page. Scroll to the bottom of the page and find information on identification and treatment for termites.
The label does not authorize to apply Bifen IT to any type of carpeting. You will want to focus treat the cracks and crevices of the room along baseboards, corners, door and window frames with a hand pump sprayer for a residual control. We advise to vacuuming consistently and sanitizing the treated area will help eliminate the fleas quicker. We also suggest using an IGR (insect growth regulator) such as Archer IGR to prevent the future infestation from developing for a better control.
While you could tank mix the two, the Mosquito Barrier is going to work against the effectiveness of the Bifen I/T for probably at least the first week or two. You are spraying Bifen on surfaces moquitoes would land on and harbor in so that when they touch the treated surface they pick it up on their bodies and die from it. If you are spraying Mosquito Barrier you are using it to repel the mosquitoes away from areas you dont want them or are trying to keep them from harboring. So essentially by mixing the two together, you are repelling the mosquitoes away from the Bifen I/T so it would not affect them. Outside of an initial contact kill the mosquito barrier isn't going to provide killing action for you long term, only repellency. Bifen is actually the better product to use on a consistent basis in main target areas on the property where mosquitoes would be found, and use the Mosquito Barrier around patios and other "hangout" areas to keep them at bay until they have died from landing on the Bifen-treated surfaces.
Per the product label, Bifen IT should be applied a coarse, low pressure, crack and crevice or spot spray to areas where pests hide, such as baseboards, corners, storage areas, closets, around water pipes, doors and windows, attics and eaves, behind and under refrigerators, cabinets, sinks, furnaces, stoves, the underside of shelves, drawers and similar areas.
Bifen IT is not labeled for use on cannabis. It likely would not harm them, as it is known for being gentle on plants, but it would not be safe to apply to anything that would be consumed in any way.