There are between 40,000 to 100,000 species of Ichneumon wasps found all over the world. They are slender with sectioned antennae and can be between 1/8 inch to 5 inches long. Generally considered a beneficial insect, these wasps prey on pest insect species. All Ichneumon species are in the family Ichneumonidae.
Where They Live
Most of this wasp species are found in forests and particularly like to inhabit dead or dying broad leaf trees. They may also be found in fields which sport lots of shrubs or that are lined with forest. Usually they live in places that are frequently damp. A few species spend most of their time around bodies of water. The only place these wasps cannot be found is where it is very dry, such as deserts, and places without tree cover, such as open plains. Most species are not found near human habitation.
Where They Breed
Ichneumon wasps are parasitic. This means that they lay their eggs inside or near the larva if other species. Usually this consists of the female manoeuvring her egg sack inside a tree, or sometimes underneath the water, to reach the eggs of another insect. The different species are usually parasitic on specific insects. For example, one species lays its eggs underwater on caddis fly eggs, another pushes its into cervices of trees so they can reach the pigeon horntail fly's eggs inside. Some even lay their eggs inside moving organisms, such as caterpillars.
What They Eat
Studies suggest that many species of Ichneumon wasps do not eat once they reach adulthood. Other species will feed from flowers, particularly those in the carrot family, taking nourishment from the flower nectar. In the larval stage, the wasps consume the larvae of the other insects they are housed with. If the wasp female laid her eggs inside a moving organism, the larva will consume it from the inside out.
What Eats Them
The Ichneumon wasps' predators are similar to most insects. Spiders and certain types of beetles prey on these wasps. Insect eating birds also pose a threat. Other parasitic wasps may prey on some Ichneumon wasp species as well. Since their range is so large, their exact predators change as the native animal life changes. For example, the predators for an Ichneumon wasp species found in North America may be spiders and birds, but they will not consist of the same species of spiders and birds that prey on Ichneumon wasps found in China.