591 A. EH. Verrill—The Bermuda Islands. 179 
will eagerly devour the eggs and young of birds, insects, reptiles, 
and any other animal food that they can find, when food is scarce, 
and they are half-starved. The early writers told of the boldness 
and voracity of the rats in killing chickens, and even entering their 
houses and eating their clothes, showing that they were unable to 
find more natural food and were nearly starved, for they do not 
ordinarily enter houses. 
At such times they probably girdled and killed many trees with 
edible bark, as other rodents are apt to do. 
c.— Effects of Injurious Insects; Snails and Slugs. 
That large numbers of injurious insects were introduced by the 
settlers, from time to time, is certain. Some of these, like the scale- 
insects, are capable of killing trees and even of exterminating species 
of plants over a limited area like the Bermudas. 
The rapid destruction of the orange and lemon trees by scale- 
insects, In modern times, is a good example of their destructive 
powers. But we know too little of the Bermudian insects and the 
effects that they may have produced on various plants, to warrant 
any lengthy discussion of the subject in this place. 
In the chapter on insects, the most important injurious species will 
be discussed, with their habits. So far as known the scale-insects 
have been the most destructive here, especially to the citrus fruit 
trees, figs, etc. (See ch. 37, j.) 
Most of the larger slugs and snails have been introduced by man. 
The most injurious of all these is the “spiral snail” of the Bermu- 
dians (Rumina decollata), which was first introduced accidentally in 
1877, at Mt. Langton, Hamilton, but it has increased prodigiously 
and has now spread all over the Main Island, doing a very great 
amount of damage tothe crops. They have here few natural enemies 
to check their rapid increase, though the Tropic-bird has learned to 
eat them. (See ch. 36.) 
Whether such snails and slugs are capable of exterminating any 
wild and common species of plants may be doubted by many, but they 
are certainly capable of interfering with their growth and changing 
the ratios of various species of plants to each other, and they might 
easily destroy rare species, or even some of the more common ones, 
in case the foliage should be particularly attractive to them for food. 
Domestic animals of various kinds are also important factors in 
altering the natural vegetation by destroying certain species that 
they prefer. Goats and sheep are particularly destructive, in this 
