So I've been battling aphids since mid-winter and I finally exhausted my big bottle of pyrethrum. I thought they were finally gone for good, after five weeks with no sightings, but today I found one on the flower stalk of my D. spathulata. I've gotten most of them, but they persist among my sundews and other leafy plants because I can't get at them in all the little nooks and crannies. I think I'm going to try flea collars next, as they seem to jump from plant to plant and I'd like to treat my whole rack all at once. I'd like to use a systemic like acephate but I don't have anywhere to put the plants to air out after treating them. (I would try drowning but I doubt it would make my cacti very happy.)
What kind of collars should I use? I figure that the size for large dogs will give the best coverage. I know they need to be kept clear of the media and water trays - how far can they be from the plants to be effective? The Savage Garden says that they should be in a tank with the affected plants - do I need an enclosure to make that work? My CPs could easily go in a tank but I'm concerned for the cacti.