The Q&A Archives: Whiteflies on Outdoor Plants

Question: I reviewed the Q & A library on whiteflies, and saw a lot of recommendations for insecticidal soap and yellow sticky traps. I'm desperate! What works well and fast on whiteflies? I started this spring with one infested lantana that I cut back and sprayed with insecticidal oil diligently. The leaves came back, and the whiteflies. They spread to other lantanas, which I later ripped out in desparation. They moved to marigolds, mums, nasturtiums, the grass - almost everything! I've since tried diazanon and malathion - following the instructions closely -and spraying repeatedly - undersides of leaves and all. I lose almost every plant I put in to these buggers. What would you do? The pesticides don't seem to be helping - but neither has anything else. I would rip out the whole garden, if necessary - to get rid of these things for good!

Answer: Whiteflies can be a terrible nuisance, but ripping out the garden seems a bit extreme! Wherever there are populations of bad bugs (whiteflies), there's a population of good bugs (such as lace wings) waiting in the wings - providing you don't kill the good guys off with insecticides! When the natural balance of predators is exterminated, whitefly populations can soar. Insecticidal soap is still your best defense, but the application must be thorough (undersides of leaves, especially lower leaves, and all the stems), and repeat applications are necessary. Instead of sprays I'd be inclined to release some lace wing insects or minute pirate bugs, to recapture the balance and eliminate the whiteflies. Patience and persistence will give you the upperhand in dealing with whitefly pests. Best of luck in your garden!

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