Hi, Judy,
In addition to picking them off, perhaps encouraging birds into the garden will help control the population. If you want an organic way to control, you could look into Bacillus thuringiensis - a bacteria that once ingested by the caterpillar, kills it within 3-5 day. The bacteria acts as a stomach poison and the good thing is it is safe for beneficial insects, bees, and mammals. It can be purchased in tablet form which gets dissolved in water that is then sprayed on the foliage.
Kathy C
Replied: Tuesday 23rd of August 2011 08:35 PM