Recently, we've been finding treehoppers, a harmful insect, in our teaching garden. Here's a message from Florence on how to find and clear the garden of these pests: 

Hi everyone, 

I want to be sure you keep and eye out for Treehoppers - the adult is very hard to spot because it's keel-shaped (like a sale, or a rose thorn) and green. It looks just like part of the plant stem.

The masses of juvenile stages, "nymphs", are quite different - blackish, and very spiney.  They are plant juice suckers and you'll often see their damage on plants before seeing the bugs themselves. Treehopper damage makes plant stems get brown and scaly, leaves drop off, the plant looks as if it's not getting water because  the bugs are sucking the life out of the stems. In our teaching garden, our wonderful Sungold tomato is under siege, also the eggplants near the tomatoes. Though they look menacing, these bugs are not to be feared -- just squish the nymphs and adults with a gloved finger. Note: the adults jump very quickly. You need to be fast! and brave!

Here are some photos for reference: 

Black nymphs and green adults

Can you spot the adult treehopper and the damage its done to this tomato plant?