Silverfish

Silverfish

Silverfish

( Latin: Lepisma saccharina)

It is probably about 300 million years ago that the first animal looking somewhat like a silverfish saw the light of day. It was doubtless very widely distributed and occurred in enormous numbers, and it has been suggested that primitive animals of this type may well have been the ancestors of all the different insect types alive today. Some insects, including silverfish, have remained more or less unchanged over long periods. Indeed, it is likely that there were primitive insects of this type when the first fish went up on to land, that they crawled around the feet of the dinosaurs, and they are still with us. Silverfish can, in fact, be regarded as living fossils, com- parable with the coelacanth.

In spite of their antiquity, silverfish have succeeded in exploiting the new opportunities created by man. In southern Europe and in parts of Asia they live out in the open, under stones and in crevices, but elsewhere they are almost exclusively associated with human habitations – houses, stables, outhouses and so on. Most people must have seen these small silvery insects run to shelter in the evening when the light is turned on in the kitchen, or may have found them in a bath or wash basin. They do not, as many believe, come up the drainpipe, but they become trapped after sliding down the smooth walls of the bath while searching for food during the night. They are particularly prevalent in kitchens and bathrooms for they require a high humidity or access to water.

Silverfish are pleasant animals which are easy to keep in captivity and they live for quite a long time, sometimes over 5 years. On the other hand, they are not very prolific, because a female will only lay about twenty eggs during the course of her life. The eggs are deposited in cracks and crevices and the young resemble the adults, except in size. Under favourable conditions they become sexually mature at an age of about six months.

Silverfish will thrive on the tiniest scraps of food, preferring starchy foods such as flour and bread (p. 59), but they also gnaw meat and are not above eating dead members of their own species. They are capable of digesting cellulose and may therefore attack books and documents. In such cases damage is not usually very serious unless the goods have been kept in a damp condition.