Tobacco hornworm with the eggs of the parasitoid wasp Cotesia congregata

Adult Cotesia wasps have laid their eggs in this tobacco hornworm (Manduca sexta). At the same time it injects symbiotic viruses into the hemocoel of the host along with some venom. The viruses knock down the internal defensive responses of the hornworm. The eggs hatch in the host hemocoel within two to three days and simultaneously release special cells from the egg's serosa. These special cells, called teratocytes, grow to become giant cells visible to the naked eye (the white stuff in the back of the caterpillar). The teratocytes secrete hormones which work in tandem with the virus and the wasp venom to arrest the development of the host. Following hatching in the caterpillar, the wasp larvae will undergo 2 molts inside the host caterpillar’s hemocoel and, after 12 to 16 days post oviposition, the 3rd instar wasp larvae will emerge out of the caterpillar and spin cocoons from which the adult wasps fly about 4 to 8 days later. For more details, please check the reference at EOL