Crawfish and raccoons, the aliens that have invaded us

The conquest of Italy by plants and animals introduced by humans began a long time ago. For example, the locust tree, which we consider indigenous, but which is, in fact, from America, was introduced into Lombardy in the 18th century. An exhibition at Villa Mirabello, in Varese, at the municipal museum, tells the story.

(in the photo, a raccoon on display, which comes from North America)

The North American grey squirrel, for example, was introduced into Italy in the 1940s, by a diplomat, who liked the fact it was affectionate towards man, but he never imagined it would be aggressive towards the red squirrel, which is perhaps less demonstrative, but is still the indigenous animal.

In the small exhibition in Varese, visitors can see a number of embalmed mammals, including some of the most common, such as the raccoon and the coypu, and read about when they were introduced.

There are also frogs, crawfish prawns and turtles preserved in aquarium tanks. For example, the Xenopus frog arrived in Sicily from Africa, and it appears to be particularly voracious. It looks quite calm in the display case, but researchers warn “Frequently, plants and animals introduced for aesthetic reasons have created disasters; it is their function in the ecosystem that we should evaluate.”

Among the photographs on display, there is one of the chestnut gall wasp, which is originally from China, which has only recently been rightly affected by the introduction of a small wasp that is its natural predator, which was introduced after a study campaign in China.

This has worked, however, the Wels catfish in the Po River, which was introduced for recreational purposes, and the Louisiana crawfish in Lake Varese, which was introduced for breeding as a food source, are still very common. “Our” red crawfish, which comes from the USA, eats a lot of larvae and insects, and this can be a problem because it devours the predators of mosquitoes.

The gambusia is a little fish that was introduced into Italy during reclamation, because it consumes large numbers of anopheles mosquitoes, and it helped us to beat malaria; but it also consumes everything else, and it is one of the North American predators included in the black list of the most aggressive and invasive species.

In the Brabbia Marsh, near Varese, the Webb parrotbill has been present for approximately twenty years. Asia and the USA are where these invaders come from, because they have the same climate as Europe; and until natural predators arrive, they will continue to operate undisturbed. Species have always moved, but slowly; sudden introductions can create imbalances. The opposite is also true. In the USA, in the 20th century, there was an environmental disaster, because fans of Shakespeare decided to introduce all of the animals mentioned in the works of the English playwright, into parks. They freed many flocks, which killed all of the native birds.

The exhibition at the Municipal Museum in Villa Mirabello can be visited from 24 November 2017 to 27 May 2018. Then, it will go somewhere else. The exhibition has been organised by Insubria University, in Varese, and Varese town council.