In addition to a favourable climate, an animal must have the right food and plenty of places to hide or shelter in if it is to thrive.
The average house certainly has plenty of hiding-places, but it does not always fulfil the other requirements. It would be wrong to suppose that the comfortable warmth of our houses throughout the year would be ideal for many invertebrates, for this is far from being the case.
The climate in our houses is very different from the summer climate outdoors in temperate latitudes. Room temperatures may be about the same as on a warm summer’s day, but the air is sometimes bone-dry, giving a desert-like climate. This is something that we our- selves may sometimes find uncomfortable, but for most invertebrates it can be catastrophic.
As a result, very few of the animals found indoors are also found outdoors. This, of course, does not apply to the many small invertebrate animals such as moths which come in through windows and doors at night, being attracted by the light. These soon die unless they can find their way out.
Most of the ‘house animals’ come originally from other parts of the world. Curiously enough, only a few of them are found living in the wild, and so it is not always possible to say exactly where they originate from, but most of them probably originated in tropical or subtropical regions. Animals with such specialized habits have probably never been numerous in the wild, and may have only become successful on entering a man-made habitat. Some of the species concerned have been associated with human habitations for thousands of years, and during this long period of time, which for insects would involve thousands of generations, they have had plenty of opportunity to evolve new types, with habits and forms that differ considerably from the original ancestral forms.
The insect and other invertebrate pests that live indoors must not therefore be regarded as casual visitors, but rather as highly specialized residents. They are relatively free from competitors and predators, and they usually have a plentiful supply of suitable food.
"Pests in House and Home"
"Bed Bugs - Bites, Stings and Itches"
"Food Pests"
"Husets dyreliv" (Insects Around the House - Only danish)
"Skadedyr i træ" (Timber Pests - Only danish)
"Stuefluen" (Common Housefly - Only danish)