The host-seeking inhibitory peptide, Aea-HP-1, is made in the male accessory gland and transferred to the female during copulation

► A biologically active peptide (Aea-HP-1) has been chemically identified from Aedes aegypti male accessory glands. ► Aea-HP-1 is transferred to the female on copulating. ► Aea-HP-1 is protected from peptide-degrading enzymes of the accessory gland. ► Aea-HP-1 is not a mosquito 'sex peptide', but probably alters host-seeking behavior of the post-mated female.