Invagination of ventral cells in early embryos is delayed compared to wild-type, but otherwise appears relatively normal.
Ventral furrow fails to form.
sna4/sna5 escapers occasionally have missing halteres. sna4/Tp(2;1)Scorv23 adult escapers are occasionally produced, which often have missing halteres or show a hemithorax phenotype. Homozygous embryos form a ventral furrow. Embryos show varying defects in the segmental denticle belts.