Homozygous third instar larvae display a reduced number of forward body-wall contractions compared to controls and the mutant larvae show frequent backward crawling. Forward crawling in the mutant larvae is often interrupted with pauses, backward contractions, head swinging and changes in direction.

β4GalNAcTA^4.1/Df(2R)β4GalNAcTA^20.1 third instar larvae also show decreased forward and increased backward movement compared to controls.

The neuromuscular junction (NMJ) of homozygous and β4GalNAcTA^4.1/Df(2R)β4GalNAcTA^20.1 third instar larvae (the muscle 6 and 7 NMJ from segments 3 or 4 has been examined) is significantly shorter than that of controls and is less branched. The mutant NMJ also has fewer synaptic boutons than normal.

The amplitude of spontaneous mEJPs and evoked EJPs is not significantly different from wild type at the homozygous or β4GalNAcTA^4.1/Df(2R)β4GalNAcTA^20.1 NMJ, although there is a significant reduction in the frequency of mEJPs in homozygous and β4GalNAcTA^4.1/Df(2R)β4GalNAcTA^20.1 NMJs.

The length along the muscle 6/7 boundary is decreased and the combined width of these two muscles is increased in homozygous and β4GalNAcTA^4.1/Df(2R)β4GalNAcTA^20.1 mutants compared to controls. This is due to hypercontraction of the muscles, as the length of individual sarcomere units is decreased in the mutants.

Mutant flies are significantly more sluggish in a climbing assay that control flies and often fail to climb at all. Mutant flies take longer to right themselves after a fall in response to mechanical agitation than control flies.