Bug of the Week: Mealybugs on Potatoes

Sometimes we find insects in places we did not expect.

mealybugs-on-sprouts-294Take these red potatoes from the grocery store. When they started to sprout, I set them aside to plant in the garden. A short time later, they looked like they were beginning to mold.

mealybugs-on-potato-sprout-301Looking closer, it became apparent it wasn’t mold at all. Insects called mealybugs were feeding on the sprouts.

mealybugs-pile-55Mealybugs are relatives of aphids and cicadas. Like some of their relatives, they are covered with a waxy powder, which gives them the white color.

freshly-molted-mealybug-44Can you spot the nymph in this photograph that has recently molted and lost its waxy covering temporarily?

sticky-mealybugs-29Mealybugs suck the juices from plants. They excrete the excess plant juices in the form of honeydew, which is a wet, sticky fluid. Scientists speculate the waxy covering helps prevent them from drowning in their own honeydew.

It turns out that scientists have already discovered that different species of mealybugs have an affinity for sprouting potatoes. In fact, people rearing mealybugs for experiments, or to produce biological control agents, use sprouting potatoes to maintain their laboratory colonies.

Looking for an easy insect to rear for a science project? Consider the humble mealybug!


  1. Eve

    Very cool! I saw these on the sweet potatoes I bought. Is it safe to eat the sweet potatoes after I cook them?

  2. Roberta

    As long as you wash off the insects first, they should be perfectly safe.

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