Adult females of onion thrips are about 1.1 to 1.2 mm long, yellow, with brownish blotches on the thorax and the median portion of abdomen. Antennae are gray with the first segment lighter than other segments.
Males are rare.
The eggs are very small, about 0.2 mm long, kidney shaped, and white. They are deposited within plant tissues. The first instar larva is white, about 0.35 to 0.38 mm long. The second instar larva is yellowish, about 0.7 to 0.9 mm long. The pupa and prepupa are similar to the second instar larvae in color and shape, except for having small wing pads.