I use Avid (Abamectin based) twice a year (early summer) at a 10-day interval (8 drops/l). After a generalized infestation with spider mites and taking into account my conditions, I bought a 8fl (236.5ml) bottle, the smallest one I found. It is good; plants do not feel anything. Before using it, I read more information found on various sites. You do not have to drink it and you have to wear latex gloves, everything is okay, it's also used for intestinal worms.