Kitchen Garden Forum

I know this isn't strictly kitchen garden, but does anyone know what happened to Plant Pins. They were wonderful in indoor plants that had whitefly etc.
Is there a similar systemic insecticide for indoor plants? I've looked and can't find anything.
All these sprays aren't so good because you have to get it on the little blighters.

Must confess my ignorance. What are plant pins? Am afraid I've never heard of them but they sound a good idea as I don't like spraying insecticide on edible plants.

They were little flat cardboard things, about 1 inch long, which you push into the soil, and when you water them, the active ingredient seeps out and goes into the plant. They were absolutely wonderful. But I've searched and searched in shops and on internet and I can't find any.