kn^col-2 mutant embryos have a significant reduction in the number of even-skipped (eve)-expressing neurons in the EL cluster by stage 15, but no difference in the number of other eve-expressing neurons (aCC, RP2, pCC and U/CQ), compared to wild-type controls.

Muscle DA3^A/DA4^T is missing or (in a few cases) reduced to a thinned muscle. This phenotype is highly penetrant and specific.

Lethality occurs during the late embryonic to first larval instar stage. Homozygous and hemizygous embryos have head defects; the ventral arms are missing and the lateralgraten are reduced. The T-ribs in the floor of the pharynx, and the antennal, maxillary or hypopharyngeal sensory organs are present and a normal pattern of internal sensory structures is seen. The embryos that hatch do not grow and tend to crawl out of the medium, suggesting that they are unable to feed.