What left the fluffy, white deposit on this zinnia stem?
This fluffy material was left by a flatid planthopper. Flatid planthoppers feed on a variety of ornamental plants. The ¼” long adults appear to be wedge-shaped and laterally flattened when viewed from above. This appearance is created by their large, angular front wings, which they hold vertically to their body when at rest. Their antennae are attached to the sides of the head below the eyes. Both adults and nymphs are powerful jumpers and can jump up to a hundred times their body length when disturbed.
Females insert eggs into the bark of trees to overwinter. Nymphs hatch in spring and summer and feed on plant sap. The nymphs are 3/16″ long and produce a thick, white, waxy secretion that has a cottony appearance. They completely cover their bodies and the surrounding stems and leaves with this substance. The wax filaments are exuded from the abdomen and are sometimes called “wax tails”. A recent study found that the wax tails help the nymphs right themselves in midair so they land on their feet. The wax is water-repellant and protects the nymphs from the rain.
The nymphs undergo five molts before emerging as an adult. They live in large colonies with multiple Flatid species in the colony. There are 1,400 species of Flatids, all with unique characteristics, though only a few common species are in our area. Some are host specific and others are generalists. They are often mistaken for mealybugs because of the white waxy covering. A quick, easy way to distinguish the two is to rub your finger across the infested plant, and the Flatids will start jumping off. Mealybugs are sedentary crawlers and do not jump.
Flatids only have one generation per year in our area and are not considered a major pest. They are primarily an aesthetic problem that only lasts about a month. The best way to get rid of them is to gently rub them off of the infested plant. Alternatively, wait a few weeks, and they will be gone, leaving no evidence of having been there.