Many commonly used pesticides are harmful to beneficial insects long after they've been sprayed, and long after pest insects are no longer affected by the pesticide. Hard to believe, that's because beneficial insects don't get sprayed with pesticides nearly as much as pests do, so  they never get a chance to build up that same level of pesticide resistance, and when they do get sprayed, because they travel around looking for food much more than pests do, they get exposed to a double-whammy dose. The best answer is to avoid use of pesticides if possible, or use those marked "S" on the table below. But if other pesticides must be used (or, have been used), please allow for the proper "wait" period before beneficial insects are introduced.This table provides an indication of the toxicity to various beneficial insects of commonly used chemicals and pesticides under "field" conditions. It should be used as a rough guide only, as many variables can affect residue persistence, especially ultraviolet light exposure. For instance, indoor environments with artificial lighting can take considerably longer than these figures for pesticide breakdown to occur, because artificial lighting of all types is much weaker in ultraviolet light (a major pesticide breakdown factor) than actual sunlight. If there's any question, you might try using some inexpensive beneficial insects such as ladybugs first, before using more expensive, more "targeted" controls.
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