Insect Hormones • A hormone is a chemical signal sent from cells in one part of an organism to cells in another part (or parts) of the same individual. They are often regarded as chemical messengers. • Typically produced in very small quantities, but cause profound changes in their target cells • Their effect may be stimulatory or inhibitory • In some cases, a single hormone may have multiple targets and cause different effects in each target • Examples of processes controlled by hormones include moulting, metamorphosis, oocyte development (vitellogenesis), colour change and diurnal rhythms of activity