RECIPE #58 PETUNIA BUG SPRAY Categories: Garden, Bugs, How to make Turns out the foliage of this pretty plant is toxic when fed to tobacco hornworm, the Colorado potato beetle and some caterpillars. You can try spraying a petunia-leaf tea solution on your plants if you are suffering an infestation. The researches at the USDA's Western Regional Center in Albany CA found that petunia leaves were enticing to the pests that they killed do your spray may bring pest to a central location and then shut them down. -----