TriStar 8.5 SL has mulitple modes of action, on contact, systemically, and through translaminar activity to control a wide variety of insects including thrips. The best treatment method would be to use a foliar spray. The label states that there should not be a soil drench application with the product.
You will use 0.125-0.253 fl. oz. of TriStar 8.5 SL per gallon of water for beetles, or 0.75-1.5 teaspoons.
TriStar 8.5 SL like with most insecticides should be applied in the cooler times of the day. As far as shelf life, be sure to store in a cool dry area where temps do not freeze or go above 95 degrees.
Per the TriStar 8.5 SL instructions on the product label: For Aphids, use 0.04 per gallon of water. Apply as a full coverage foliar spray with a nonionic spreader-sticker adjuvant. When mixing with surfactant treat a small area first to make sure the surfactant does not cause phytotoxicity. For Fungus gnat larvae, use 0.085 to 0.165 fl oz per gallon, ase the higher rate when insect pressure is high. Apply as a directed spray to thoroughly wet the upper 1/2 to 1 inch of soil media.
TriStar 8.5 SL is safe when used as directed. We would recommend applying when they are not in the area and would not be for at least a few hours after so evening is good.
Safari 20SG for containerized plants in a greenhouse to treat sucking pests like mealybugs. We recommend contacting a Master Gardener in your area for recommendations on succulents since they may require different treatment than other ornamentals.
TriStar 8.5 SL is not labeled for use on Christmas trees, so we would not recommend this application. Safari 20SG is labeled for use on Christmas trees (including fir) for cryptomeria scale. You will use ¼ – ½ lb (4-8 oz) per 100 gallons of water and apply as a foliar spray, or use 0.2 – 0.4 oz per 1000 sq ft. For small areas, use ½ – 1 tsp per gallon of water. Make first application just before pest populations reach an economic threshold. If necessary, make a second application after 14-21 days. Tank mixing with a surfactant may improve control of scale. You could also use a horticultural oil or dormant spray such as Brandt TriTek for a foliar spray.