hy birds of tJie Covinion Eariuig (Forficula auricularia) 173 



It seems established that a large number of ordinary garden 

 species are liable to serious attack by earwigs, and that the latter 

 can continue healthy on a purely vegetable diet. But much further 

 information of a detailed kind is required befoi'e we can explain 

 why in a given locality a particular kind of plant is attacked 

 while in another it is neglected. Does it mean that the presence 

 or absence of suitable animal food is a factor ? 



As regards animal food, there is a considerable amount of 

 evidence that earwigs are often carnivorous by choice, very 

 possibly they are so usually (cf Rlihl, M.T. Schweiz. Ges. vii. 

 1887, p. 310). In respect of eating dead animal matter I have 

 found that when kept in captivity they devour the soft parts 

 of their fellows who have died even when fresh vegetable food 

 is available. In this necrophagous habit they resemble cock- 

 roaches. Jones {op. cit.) states that dead flies and dead or dying 

 comrades are devoured. Lustner (op. cit.) finds that only dead 

 animal matter is taken. This conclusion points to too limited an 

 inquiry and want of taking into account the possible presence of 

 food plants which were more attractive than available living prey. 

 In any case his opinion that earwigs should not be regarded as 

 beneficial is traversed by the records of their killing certain insect 

 pests of plants. 



Round Island, the northernmost islet of the Scilly group, is 

 swarming with earwigs, and they congregate in vast numbers in 

 the light-keepers' midden inside the discarded pressed beef tins. 

 If, as seems probable, they reached the islet before the lighthouse 

 was built a change of diet seems to have occurred, as the indigenous 

 vegetation is chiefly Armeria maritima, Cochlearia officinalis and 

 Mesembryanthemum edide. There is no turf It is of course 

 possible that they seek the potato peelings also thrown into the 

 midden and that their numbers inside the discarded tins mean 

 that the latter are frequented partly for shelter. If the Round 

 Island earwigs have really turned during comparatively recent 

 years from a herbivorous to an extensively carnivorous diet, 

 Rosevear, another islet of the Scilly group may, in a sense, be a 

 converse case. It is the other locality in the Scilly group in which 

 (as far as I know) the earwig population is densest. Like Round 

 Island, it is very small, but differs from it in being uninhabited. 

 But from 1850 to 1858 it was occupied by the builders of the 

 Bishop Rock Lighthouse, so is it possible that the abundance of 

 earwigs is due to the animal food available in the past ? However 

 this may be the present diet of the Rosevear earwigs appears likely 

 to be vegetarian in the main, unless the islet harbours some insect 

 or other small arthropod suitable for food. The commonest plants 

 are Armeria maritima and Lavatera arborea, the latter growing 

 luxuriously. But before the abundance of earwigs on Rosevear 



