Insects (mostly wasps and flies) in which the adults are free-living, but eggs are laid in, on or near an insect host (or rarely, a spider or isopod), after which the parasitoid larva develops in the host (itself usually a pre-adult), initially doing little apparent harm, but eventually consuming and killing the host before or during the pupal stage.
An organism that lives at the expense of another (its host), impedes its growth and eventually kills it. Insect parasitoids, which are often very tiny, attack a single organism (plant or animal), from which they derive everything they need for their own growth and reproduction. One way a parasitoid does this is by laying its eggs in the body of the host insect. Parasitoids are being used more and more for biological control of insect pests, thus reducing the need for chemical insecticides. Predators, unlike parasitoids, prey on more than one organism and kill and consume their tissues.
An organism that, during its development, lives in or on the body of a single host individual, eventually killing that individual. Larra wasps, Ormia flies, and Steinernema nematdoes are examples of parasitoids; note that the wasps and flies feed during their larval stages, while in the adult stages they feed on the nectar of plants. Many people use the word parasite when they really mean parasitoid; this is unfortunate because it obscures the lethal effect of parasitoids.
A parasitoid is an organism (a plant or animal) that lays its eggs in or on another living organism (the host). The eggs hatch and feed on the live host tissue. Some wasps are parasitoids; they lay their eggs in a caterpillar's body. When the eggs hatch, they feed on the caterpillar and eventually kill it.
pahr-eh-syT-toyd) An organism which lives in or on another organism. This is typically a micro-micro or macro-macro relationship which is temporary. The host typically dies serving the parasitoid, often being no more than an incubator, food source, and nursery for the parasitoid's offspring. The relationship is never symbiotic.
A parasitoid is an organism that spends a significant portion of its life history attached to or within a single host organism which it ultimately kills (and often consumes) in the process. Thus they are similar to typical parasites except in the certain fate of the host. In a typical parasitic relationship, the parasite and host live side by side without lethal damage to the host.