Hydrolyzes one beta-GlcNAc unit at a time from the non-reducing ends of substrates, with a preference for shorter substrates. The 2-acetamido group and the beta-glycoside bond linkage in the substrate are required for its activity. Active with p-nitrophenyl (pNP)-beta-GlcNAc, pNP-beta-GalNAc and chitooligosaccharides (degree of polymerization from 2 to 6), but not with the complex N-glycan substrate (GlcNAcbeta-1,2Manalpha-1,6)(GlcNAcbeta-1,2Manalpha-1,3)Manbeta-1,4GlcNAcbeta-1,4GlcNAc-PA (GnGn-PA), pNP-alpha-GlcNAc or with the long polymer colloidal chitin. Involved in chitin catabolism (PubMed:18959754). Involved in the degradation of old cuticle during the pupation stage (PubMed:21106526). Hydrolysis of terminal non-reducing N-acetyl-D-hexosamine residues in N-acetyl-beta-D-hexosaminides. Inhibited by O-(2-acetamido-2-deoxy-D-glucopyransylidene)-amino-N-phenylcarbamate (PUGNAc) (PubMed:21692744). Inhibited by thiabendazole (TMG)-chitotriomycin (PubMed:21692744, PubMed:21106526, PubMed:23300622). Inhibited by 6-(dimethylamino)-2-(2-(((5-methyl-1,3,4-thiadiazol-2-yl)methyl)amino)ethyl)- 1H-benzo[de]isoquinoline-1,3(2H)-dione (Q2), a synthesized non-carbohydrate unsymmetrical dyad of naphthalimide and thiadiazole having a dimethylamino group at C4 of the naphthalimide (PubMed:25155420). Inhibited poorly by N-acetyl-glucosamine (NAG)-thiazoline (NGT), but when the thiazoline ring of NGT is replaced by a bulky substituent such as in compound 1,2-dideoxy-2'-methylamino-alpha-D-glucopyranoso-[2,1-d]-Delta2'-thiazoline (NMAGT), the inhibition constant Ki is lowered 600-fold compared to that of NGT (PubMed:25436416). Inhibited by berberine, berberine analogs thalifendine and palmatine, and berberine derivative SYSU-1, but not by berberine analog tetrahydroberberine (PubMed:30135205). kcat is 934 sec(-1) with GlcNAc-beta-1,4-GlcNAc as substrate. kcat is 708 sec(-1) with p-nitrophenyl-beta-GlcNAc as substrate. kcat is 766 sec(-1) with p-nitrophenyl-beta-GalNAc as substrate (PubMed:18959754). kcat is 434.7 sec(-1) with 4MU-beta-GlcNAc as substrate. kcat is 507.4 sec(-1) with GlcNAc-beta-1,4-GlcNAc as substrate (PubMed:21106526). Optimum pH is around 7.0. Optimum temperature is 30 degrees Celsius. Stable up to 40 degrees Celsius. Homodimer. Expression is dramatically up-regulated at the wandering stage. Low expression at fifth instar larva (day 1), prepupal, pupal (days 1 and 2) and adult stages (PubMed:18959754). Expression is up-regulated before each molting stage during development of the late fourth instar larva (4L), late fifth instar larva (5L), prepupa (PP), and late pupa (P3). The expression level reaches its peak at the fifth instar day 5 (5L5) and prepupa stages, and the level is about 10 times higher than that of fifth instar day 3 (5L3) larva. At the 5L3 stage, expression levels in the integument and alimentary tract are similar. However, at the 5L5 stage, the expression level in the integument is up-regulated more than 3-fold, but remains unchanged in the alimentary tract (PubMed:21106526). RNA interference of this gene does not cause any visible changes in phenotype in larvae before pupation. At the pupation stage, 20% of the larvae show abnormal phenotypes. They fail to shed their old cuticles completely before starting to form new ones underneath. A potential target for eco-friendly pesticide development because of its species specificity and narrow substrate spectrum (PubMed:18959754). Q2, the designed non-carbohydrate naphthalimide-based inhibitor against this enzyme has potential use as pharmaceutical or pesticide as it selectively recognizes chitinolytic beta-GlcNAcases, but not glycoconjugate-lytic beta-GlcNAcases (PubMed:25155420). Belongs to the glycosyl hydrolase 20 family.