A new class of N-alkyl or N-alkenyl, 2,3-dihydro-4-thioxo-2H-1,3-benzoxazin-2-ones is disclosed. This class of compounds is useful in the control of plant pests. Thus, pesticidal compositions comprising these benzoxazin-2-ones with a carrier therefor are also described. In addition, a process for forming these benzoxazin-2-one compounds is also set forth.