Termites eat wood that may have sharp particles (splinters) and many microorganisms. The digestive system of insects is vulnerable to piercing by sharp objects and that could lead to infections by bacteria or other micro-organisms. The foregut of the insect is lined with cuticle, a similar type of material to that found on the outside of the insect. The Midgut, however, cannot be lined with cuticle because the cells of the midgut must be able to transport nutrients directly from the fluid in the lumen of the gut.
To protect the midgut from the food, termites and other insects secrete a membrane, the peritrophic matrix that serves as a barrier between the food and the cells of the midgut. The peritrophic matrix is permeable to nutrients and digestive enzymes, but prevents large particles of food (and many microorganisms from contacting the cells and damaging or rupturing them.
Ramos and colleagues* published a beautiful microscope image of the midgut of the Formosan termite that clearly shows the peritrophic matrix (PTM) in the image below. The peritrophic matrix of termites is of interest to entomologists as a biomaterial, but also as a potential insect control target that is unique to arthropods. Agents that could attack or damage the peritrophic matrix could potentially be used to control termites and other pest insects.
*Peritrophic Matrix of the Formosan Subterranean Termite (Isoptera: Rhinotermitidae)
J. A. Morales-Ramos, M. G. Rojas, H. Sittertz-Bhatkar. Florida Entomologist, 89(1):99-101. 2006.