A polyclonal antibody raised against allatostatin-3 ofBlattella germanica(BLAST-3) has been used to immunolocalize allatostatin-like peptides in the brain-retrocerebral complex ofLabidura ripariaadult females. Strongly stained immunoreactive cells are observed in thepars intercerebralis(14 cells) and mainly in thepars lateralis(32 cells). Fibres leading to thecorpus allatumare also stained. In the deutocerebrum, one cell is immunostained at the root of each antennal nerve. In the tritocerebmm two cells in each brain hemisphere are weakly immunostained. During the reproductive cycle, these cells and their axons show immunoreactivity at previtellogenic, ovulation and ovarian arrest periods. During vitellogenesis, immunoreactivity is restricted to only four perikarya in thepars intercerebralis.