Oh! I just found out that a book I own is now online in an updated version:
Field Guide to Common Insect Pests of Urban Trees in the Northeast

Since it’s the time of year to look for these things, here’s the page on oystershell scales, which I have in abundance on my lilacs. Grrr.

Now is a great time to treat scales with dormant oil sprays. From that Extension publication:

“Proper timing is critical for success when using oils. Dormant oils should be applied in late March or April before leaves or flowers show signs of breaking dormancy; that is, before “bud break.” A common mistake is to apply ‘dormant’ oil sprays too early (on the first warm day in February or March) before insects are actively respiring and susceptible to the oil’s suffocating effects. Wait until as close to bud break as possible before applying oil sprays. “

Posted by Gwen Pearson

Writer. Nerd. Insect Evangelist. Have you heard the good news? BUGS!


  1. Scales are tough to kill. Good luck! :)

  2. OK, so when I go to my local hardware/garden store, what am I to ask for? Is there a common name brand on the market?

  3. well, I usually just ask for dormant oil at the awesome local nursery, but the average big box chain store won’t have a person that will know what that is.
    I usually find it next to safer soap.

    Google has some suggestions.

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