Bug hotel: a home for Bugs

Goals

The project, result of an agreement between the Park and two private entities: “Unifarco per il territorio” and “Dolomia”, involves the installation, in 4 points of the Park, of bug hotels: wooden structures offering shelter to several species of Insects, such as wild bees, butterflies, ladybugs, and chrysops (insects with transparent wings feeding on aphids).

In the Park, the natural environment is intact and there is no lack of shelters for insects; the installation of bug hotels has therefore an educational function, because it facilitates the insect observation and draws the attention of the Park visitors to the problem of the pollinator decline and to the fundamental importance that these small animals represents for the very survival of humankind on Earth.

Let’s save pollinators!

Many plants need pollinating insects to reproduce.

In addition to the European honey bee, there are thousands of species of pollinators: wild bees, hover flies (small colourful flies that seems to be wasps), butterflies and Coleoptera.

There are 2,000 species of pollinators in Europe, which ensure the existence of 78% of wildflower species and 84% of cultivated species.

Without pollinators we would not have, for example, apples, citrus fruits, strawberries, beans, cucumbers, tomatoes, and peppers.

The European agricultural production guaranteed by pollinators is worth 15 billion euros per year.

Today pollinators and Insects in general are in decline, due to the environmental degradation and pollution, excessive use of pesticides in intensive agriculture.

In Europe one out of 10 species of bee or butterfly is in danger of extinction.

The Alps are one of the richest areas for pollinators, with 600 species of wild bees, but half of these now risk extinction.

The intact environments of the Park are home to many pollinators: recent studies, carried out in collaboration with the University of Bologna, and the Mach Foundation have identified 67 species of wild bees and bumblebees only in Vette Feltrine and 174 species of hover flies throughout the Park.

Bug hotels

Bug hotels are wooden structures containing different types of artificial shelters (pieces of marsh canes, perforated wooden blocks, straw tufts,…). These shelters are used by different types of Insects to reproduce (as in the case of many solitary Bees, which nest inside the hollow stems) or to find shelter during the winter (as in the case of some species of butterflies and ladybugs).

The project involves the installation of 4 bug hotels in as many locations in the Park:

• the picnic area of Pian d’Avena (Pedavena);
• the Environmental Education Centre “La Santina”, in Val Canzoi (Cesiomaggiore);
• the botanical garden of the Campanula morettiana Park in Val del Mis (Sospirolo);
• the Pramper alpine hut (Val di Zoldo).

Below are some information sheets on the pollinators that use bug hotels or that can be observed nearby.

Solitary bees: the Mason bees

Everyone knows the European honey bee, which lives in large families; but there are also many bees living alone. They are called “solitary bees” because, unlike the domestic ones, they do not have any form of social life; among the most common are those of the genus Osmia (up to now 7 different species have been found in the Park).

Each female Mason bee, after fertilization, looks for small natural cavities (such as tunnels dug in the trunks by xylophagous insects, empty canes, cracks in the rock) or artificial ones (such as those of bug hotels).

The cavity is covered with mud, or plant material mixed with saliva, and divided into many small cells, where the Mason bee accumulates reserves of nectar and pollen. In each cell, an egg is laid, and the larva feeds on the food accumulated in the cell.

The larva transforms into an adult bee at the end of the summer, but remains in its cell until the following spring, when it will leave the nest by breaking the mud “door” closing it.

The males are born from the eggs laying closer to the exit. In spring, they come out of the nest before the females and wait for them to mate.

Some species of Mason bees exploit, to build the nest, the empty shells of snails, while others are bred by humans in artificial nests and sold to farmers, who use them for pollination of orchards.

Hover flies: flies disguised as wasps

Hover flies are a family of Diptera (“relatives” of flies and mosquitoes) which imitate bees and wasps in shape and colour. In this way, they deceive predators into thinking they have a stinger, but they have not (scientists call this type of imitation Batesian mimicry).

The adults of the hover flies feed on nectar and pollen and are formidable pollinators, second in importance only to the Hymenoptera (bees and bumblebees). In cold environments such as high mountains, their role as pollinators can be even greater than that of the Hymenoptera.

Hover flies can hover in stationary flight, like helicopters, over the flowers they visit to feed.

At the larval stage, hoverflies have very varied feeding habits. Several species are carnivorous and feed on aphids, but there are larvae eating mushrooms or plants and many species are saprophagous, i.e., they live off decaying organic matter, such as rotting wood and can only live in forests with mature trees.

Some species have aquatic larvae, with a long siphon rising to the water surface and it allows them to breathe (they are called “rat-tailed’ maggots”, because of their shape). There are more than 6,000 species of hover flies in the world, with almost 900 in Europe, over 500 in Italy and 174 in the Park.

Schmetterlinge: die auffälligsten Bestäuber

In the adult stage, most butterflies feed on nectar, taken from the flowers using the suctorial proboscis: a mouthpart in the shape of a long, coiled proboscis, which is everted to reach the sugary liquids contained in the flowers.

When visiting flowers to feed, the butterflies transport pollen from one plant to another, enabling them to reproduce. Recent studies have shown that not only daytime butterflies, but also so-called “nocturnal” butterflies play a very important role as pollinators.

Among the guests of the bug hotel are also butterflies, species that spend the winter in the adult stage, such as the European peacock (Aglais io) or the small tortoiseshell (Aglais urticae): among the most common and widespread species in the Veneto.

To date, 106 species of diurnal butterflies (almost 40% of all species present in Italy) and 435 different species of moths have been observed in the National Park.

Among the diurnal butterflies, 12 species are considered at risk of extinction in Italy or in Europe and find, in the Park, favourable conditions for their survival, such as the Apollo (Parnassius apollo): one of the most famous and elegant alpine butterflies. In order to preserve the butterfly populations, the Park has resumed mowing old, abandoned meadows, to prevent them from being invaded by shrubs and woodland, and thus maintain favourable environments for their reproduction and development.

Ladybirds: the aphid-eaters

Among the guests of the bug hotel are ladybirds.

These colourful beetles usually overwinter as adults, gathering in large numbers in small crevices and shelters, such as those offered by the bug hotel.

To date, around 6,000 species of ladybirds have been described worldwide. Almost all of them are predators, both in the juvenile and adult stages.

Among their favourite prey are aphids (the “plant lice”): parasites that cause direct damage to plants (because they feed on sap, extracting it from the plants with their mouthparts) and indirect damage, since they can be vectors of dangerous viruses and because fungi an develop on their sugary excrement (honeydew).

Ladybirds help to reduce aphid populations: a ladybird can eat up to 5,000 aphids in its lifetime!

Many species of ladybirds feed instead on scale insects: other dangerous pests of many cultivated plants.

Many ladybirds supplement their aphid diet with nectar, so they can visit flowers, and act as pollinators, albeit to a lesser extent than other insect groups (such as bees, bumblebees or butterflies).