The Asian citrus psyllid (ACP; Hemiptera: Psyllidae) is a tiny (0.125 inch, 3 mm, in length) mottled brown insect that is about the size of an aphid. The adult psyllid feeds with its head down, almost touching the leaf, and the rest of its body is raised from the surface at a 45-degree angle with its tail end in the air. No other insect pest of citrus positions its body this way while feeding.
Adults typically live one to two months and develop more quickly in warmer weather. Females lay tiny yellow-orange, almond-shaped eggs in the folds of the newly developing, unfurled, soft leaves, called the feather flush. Each female can lay several hundred eggs during her lifespan. Nymph development is limited to the flush or new growth of citrus. Nymphs are typically yellow-orange but can also have a green hue and lay flat on the surface of new feather flush (young instars), edges of leaves, and stems of flush (older instars). Nymphal development slows at 104°F and continual exposure to 3 or more hours per day of 108°F causes nymphal mortality with no development into adults. Similarly, temperature affects ACP dispersal with high temperatures reducing flight.