Scales

Scale insects, which vary in size and shape, secrete a waxy coating for protection and defense. The waxy coating presents as a scab-like appearance that is attached to the leaf or fruit / berry, and the insects live under the coating. Each female can lay 100-150 eggs, which hatch into baby insects called crawlers. The crawlers often leave the scale to find their own homes in leaves or fruit / berry. Clearly, then, a scale may indicate the
presence of insects safely hidden by the waxy coating.

Thus, any produce item with a scale, such as blueberries, should be discarded. Citrus fruits that look clean are clean, since scales are very visible.