The paper presents the results of measurement of the total cross sections for reactions 4,6 He + Si and 6,7,9 Li + Si in the beam energy range 5−50 A⋅MeV. The enhancements of the total cross sections for reaction 6 He + Si compared with reaction 4 He + Si, and 9 Li + Si compared with reactions 6,7 Li + Si have been observed. The performed microscopic analysis of total cross sections for reactions 6 He + Si and 9 Li + Si based on numerical solution of the time-dependent Schrödinger equation for external neutrons of projectile nuclei 6 He and 9 Li yielded good agreement with experimental data.