With nights in the upper 40s this week when many plants can be left out of the greenhouse over night, spring-cleaning is in full swing. A major aspect of spring-cleaning is finding any bugs and taking care of them. This is the best time because all the surfaces can be cleaned and sprayed.
I am not finding many visible bugs but there could be small groups of plants with an infestation, so every plant gets looked at. For an individual plant the first step is removing anything brown and inspection. If I see any bugs, I spray them with an alcohol-soap-water mix. I have added red coloring to the soap so that I know for sure that the spray bottle contains the alcohol, not water.
The next step is washing off all the bug bodies. When I re-inspect a plant in a couple of days, I know any bugs I see are new bugs. I use a spray bottle with a pretty strong stream of water.
Whether I have seen bugs or not I spray the whole plant with Bayer insect killer. Young bugs are small and can be on a plant without being seen. If I am re-potting, I spray the roots as well. This gives about a month of protection according to the label, but there is a lot of water spraying in my greenhouse and it probably is gone in a week.
What has been effective for bug control is the Bayer systemic. I mix it weaker than label directions and add a quarter-teaspoon of 20-20-20 fertilizer to my gallon pump sprayer. Since I started using it I have not seen any meally or aphids at all. Scale is not gone but definitely under control.