Here is another picture, if this helps. Bob

Imidacloprid works every time for me and it's never injured any plants no matter how much I put on.

Maybe yours had some other ingredient. I would get a different formulation and try again. Remember it kills scale but it doesn't remove it. You'll know it's dead though if it's easier to remove mechanically.

it has spread to many new plants, which are all crowded together in my greenhouse.

This will be the main reason why you are getting it.

Growers,

Thanks for the input. I'll try to get them all cleaned up and see if I can get rid of this stuff at last. Your help is appreciated. Bob

Words of caution about using oil based chemicals on bromeliads. They can damage if not used properly

Oil and malathion will definitely damage bromeliads. The suggested methods are very labor intensive and not very effective. I am not convinced that dumping oil on the ground is any better for the environment, either. The best thing to do would be to foliar spray imidacloprid three times, every two months or so, to exterminate the subsequent generations of scale. Get a formulation with no other active ingredients to avoid damaging the plants.

If you have to put your plants in a greenhouse they're going to be crowded. Mine also have poor air circulation, constant 100% humidity, dripping condensation, etc, and yet they hold up fine. Bromeliads are VERY tough greenhouse plants. They have few pests and the ones (like scale) are easily controlled. Most varieties survive the crowding, short days, low night temperatures, etc., without any problem. I did have some problems with a few varieties but it seems to have mostly gone away this year when I raised the nighttime temperatures to 38 degrees.

Thanks for your input and ideas. I have ordered some Garant and will start treating regularly until I get rid of this stuff. Bob