This thesis examines the insect immune system using the cockroach, Periplaneta americana as a model. Host immunocompetence has been investigated by studying the cellular immune response to infection with Moniliformis moniliformis (Acanthocephala) and Hymenolepis diminuta (Cestoda) . Studies of this nature are relevant to medicine, veterinary science and agriculture because of the deprivation and suffering caused by insects as disease vectors and as pests. A general introduction (Chapter 1) provides information on the lifecycles and biology of the parasites used in this study and gives an overview to the study of invertebrate immunology, emphasising functional aspects of the insect cellular immune response. In Chapter 2 the experimental procedures used throughout the work are detailed
