Some insects (eg bees) orient themselves to the sky. A ground cover might confuse such insects. A mirror like reflector might have aphids crawling all over themselves crawling on reflected undersides of the leaves actually above them. (note this is only speculation. But it is quite a treat to watch a bee fly over a new bright galvanized hive cover and in the space of a few inches do a 180 roll to fly upside down.) >At 04:26 PM 2/20/99 PST, you wrote: >>Somewhat on this same topic, the farmer I mentioned who uses red plastic >>for tomatoes uses silver plastic mulch for eggplant (even though they >>are in the same family). He says it does a better job at keeping off >>aphids, but I wonder if there is something else going on. --