There may be others that think that it is no big deal, but I would NOT use a pesticide like this indoors. In fact, it would not be my first choice outdoors either. The fact that your cactus still reeks of the stuff should tell you something right there!! Try typing malathion into any search engine and see what you find...even if it is just going to be used systemically, and not sprayed, I still would not want it in my house. I could also go into a long tirade on what the using of these pesticides is doing to the enviroment, but this isn't the place for that. I just think that hard core poisons should only be used as a very last resort and in extreme situations.

A few mealies should be easy to eradicate with either rubbing alcohol or soapy water. I usually just use Safer brand insecticidal soap, which is pretty safe, and even that I apply outdoors and leave the plant outside for a day or so..you can buy it everywhere, either in a spray form or concentrated that you mix yourself - drench the plants foliage, making sure to get under the leaves. Repeat every couple weeks for a month or so, and that should do the trick!

ps- if you decide to try the rubbing alcohol, DO NOT get the alcohol on the soil surface, it will sink down to the roots and that would not be a good thing...and make sure the plant is not in direct sun during or after spraying. I think some people dilute the alcohol with water first.

A few mealy bugs are no big deal, just treat and isolate and you and your plants will be fine!!

Please, PLEASE don;t use this on anything you are going to keep in your house! Malathion is one of the worst perticides around. When we lived in Los Angeles in the mid to late 1980's they were battling the Mediterranean Fruit Fly, and they would do aeriel bombardment at night, using helicopters, and drop malathion impregnated into a corn syrup base over different parts of the city. They would always warn everyone on the nightly news, because, if the stuff got onto your car and you didn't get it off right away it would scar the paint! Also, they warned to take all outdoor pets inside and for people to stay indoors too! And they wonder why the bees are in decline today!

It would be far better to just mix up some dishsoap in water with a tsp of rubbing alcohol and spray your plants, or, better yet, take them outside and spray with Neem Oil and leave outside for a couple weeks so natural predators could help you out

Malathion works great outdoors, and it breaks down quickly if on organic matter, especially when the sun is shining. However, it is NOT safe to use indoors because it decomposes at a slower rate, and that includes going through a stage where it is malaoxon, which is reported to be more toxic than the original malathion.

I would not be worried about using it outdoors, however. I have found it to be a very reliable outdoor insecticide for many purposes (I do, however, try the soap spray first on ornamentals).

While, to be certain, malathion is an old organophosphate insecticide, people often make it out to be worse than it is. When people talk about the effect it could have, for example, on paint on a car, that is largely because of its surfactants - it is suspended (at least in part) in petroleum distillates, and often when sprayed as a mosquito/med fly fog, it is mixed with other oil-based products. This especially affected old paint jobs.

One thing you said strikes a chord, smikes..."petroleum distillates". Depending on the plant species, some can handle that better than others. Some genera of orchids, for example, are very sensitive to petroleum distillates and will be damaged by usage of an insecticide that incorporates them. Many years ago people were using Orthene on orchids and finding that some were severely damaged or even killed, and it was discovered that it was the petroleum distillates. There is a wettable powder form of Orthene that's much harder to find, but doesn't contain the bad stuff, that is less damaging. I personally would do a "spot check" of anything I planned to spray with Malathion and wait for a day or 2 and see if it damages the foliage before I spray the whole plant.

I did once wing it by diluting and using as a drench for plants before bringing larger ones inside for the winter. I need someone to tell me what proportions are actually acceptable. plant plants wewere fine.