| I’m not sure if the cabbage butterfly caterpillar that you have is the same as the one we have here since there is always some confusion with common names. It’s the same with products; I’ve never heard of Derris dust before but do know of Pyrethrum and Rotenone. I wanted to suggest the use of "Bt" that can be purchased in liquid form as a solution for your caterpillar problem. While searching for information on Derris dust, I found this page that also mentions Bt - http://www.organicnz.pl.net/pastissues/janfeb01/pesticidesjanfeb.htm. From that page is this quotation ..."Derris Dust is a restricted material, meaning that it may be used "only in accordance with the principles specified in these Standards", with a reduction each year in the dependence on it, and only until more acceptable materials are available. It is also permitted under Demeter and Agriqual/Certenz standards. Its main use is in home gardening, particularly for controlling the caterpillar of white cabbage butterfly. In commercial horticulture it has largely been replaced by Bt preparations. Bt is the short name for Bacillus thuringiensis"... . There are many different varieties of Bt; maybe your local agricultural agent could give you some direction. Terran |
Here is a link that might be useful: PARKINSON'S DISEASE, PESTICIDES AND DERRIS DUST
