Thank you, Wong. I hadn't noticed any pests, but after I read your message, I checked carefully. Indeed, on the underside of each leaf was one or two tiny white flies, about .75 mm or less in length. They looked like "micro-moths", and flew when disturbed. In addition there was some evidence in the form of a few droplets of dried liquid, and a few small splotches of a brown powdery substance around some of the vein junctions on the leaf underside. I took the expedient method of dealing with this... I gave each plant a brief blast of Raid House & Garden spray. The main active ingredient is indeed Pyrethrin. We will see what happens next. ...Ed.... Che Wong wrote: > > Hi Ed, > > I looked at the picture of your plant. My guess is that on the > underside of the leaf, you have some sort of bug chewing into and > sucking juices from the leaf. My experience is that leaf curling > is usually associated with scarring of the tissue. As for the yellow > splotches, it may also be a symtom of the parasite or it could be > something else. Most bugs will leave some sort of sign on the underside > of the leaf; it may be a powdery film, droplets of plant sap or some > other evidence that will make it different than a leaf from a normal > plant. <snip>