The immatures of the New World treehopper tribes Acutalini Fowler and Micrutalini Haupt (Hemiptera, Membracidae, Smiliinae).

The nymphs of Fairmaire, Sakakibara, Kirkaldy, and Fowler are described and illustrated ( and for the first time). The nymphs of all four genera are exceedingly cryptic. The nymphs of some species lack scoli on the head and pronotum but all have paired scoli on the meso- and metathoracic nota and abdominal segments III-IX. Some species also have lateral rows of enlarged chalazae on the abdomen, and even large scoli ventrolaterally-the latter condition is unique within Smiliinae. The eggs are deposited in stems (not in exposed masses) and nymphs are solitary and not ant-attended. The fifth instar nymphs of Micrutalini range in length from 3.0-3.5 mm, much smaller than the fifth instars of most other treehoppers.