Neem Oil vs Canola Oil To Control Squash Bugs


 Can I use Canola Oil mixed with Insecticidal Soap to control Squash Bugs in my organic vegetable garden, or is Neem Oil better?


  • Canola Oil, mixed with Insecticidal Soap and Neem Oil, is recommended to Squash Bugs on the UC Davis Integrated Pest Management (IPM) website.
  • While I have no problems with Neem Oil or Insecticidal Soap in home gardens, I'm leery of using Canola Oil as there are no posted dilution or application rates. With the wrong application rate, you could very easily burn the plants in warm weather.
  • Squash Bugs, often referred to as Stink Bugs, are difficult to control in large quantities; hence, you need to be proactive early, much like Whiteflies. They prefer crookneck or yellow straight-neck squash but not zucchini. You can also find them on pumpkins, cucumbers, along with the winter squash varieties.
  • Squash Bugs cause the vines to turn black and die while the insect feeds on the foliage and the maturing fruits. In organic gardens, there are several strategies you can use that don't require spraying. If only a few plants are affected, the most effective control method is manually removing and destroying the adults and eggs.
    • The adults are about five-eighth of an inch long and a quarter of an inch wide. They're a grey or black color with orange and or brown stripes on the edges of their abdomen. The eggs are a shiny, yellowish-brown to reddish color. You'll find them on the undersides of leaves, lined up in neat rows near the base of the main vein.
    • The eggs are clearly visible to the naked eye, so you should be on the lookout for them starting in May through mid-summer. They're easily destroyed by gently rubbing them back and forth with your fingers, but make sure you don't damage the leaf. Between the adult and egg, the white to greenish-gray colored Nymph is present.
    • Nymphs have no wings, although they do have legs and mature into adults in four to six weeks. You find them near the base of the plant and the vines beneath the foliage and developing squash. Another option is to place cardboard strips or shingles on the ground next to the plants.
    • The squash bugs will gather in the morning under the boards, making it easier to eliminate them. Catnip, radishes, nasturtiums, and marigolds are purported to repel Squash Bugs, to some degree so that companion planting could be considered.
  • At the end of the season, remove all the leftover debris. Good sanitation practices eliminate hiding places for the bugs to overwinter. And finally, you can spray with Neem Oil, Insecticidal Soap, or Spinosad. My preference would be Neem Oil or Spinosad.

NOTE:  Scientists believe that Canola Oil repels insects by altering the outer layer of the leaf surface or by acting as an insect irritant. Like other vegetable oils, Canola is safe for most plants and won't harm humans or pets. However, the effect of canola oil differs depending on the pest. For example, canola oil may poison some bugs or blocks insects' air holes, causing them to suffocate. I would avoid spraying Maples, junipers, cedars with any type of oil.