Thanks Babka - good heads-up - appreciated.

A little more info:

AKA - jumping plant lice

One of the most important means of identification is the psyllid sugar that is excreted by the insect and collects on leaves.

Among insecticides available to homeowners, products containing permethrin or esfenvalerate are most effective when used at rates labelled for other potato/tomato insects. Alternately dusts of sulfur can provide control. Regardless, application must be thorough, covering the underside of lower leaves where the insects tend to concentrate. Insecticidal soaps (two percent concentration) may also be useful, although control is more erratic.

Some tomato varieties appear to be partially resistant to potato/tomato psyllids. Increased hairiness of the leaves is reported to make plants less favored by psyllids.

Here is a link that might be useful: Potato or Tomato Psyllids

I really soaked mine with Spinosad (Organic Captain Jack's Dead Bug Brew). Two days later, no sign of any sugar deposits. I will be spraying again as my plants are very thick and I want to be sure to get every inch of the undersides of leaves where those darn psyllids are living.

-Babka

The crystalline material is the psyllid version of honeydew.

Hi Babka! Good luck with those psyllids...hope they don't cause too much trouble. They don't like hosta, do they??