ENEMIES AND THEIR INFLUENCE. 399 



unfrequently the eggs are destroyed by vegetable mold. According to the 

 observations of Homburg, house spiders in the kingdom of Naples are sub- 

 ject to a malady which makes them appear hideous. Their body 

 Mold, becomes covered over with scales, bristling one above the other, 

 B - , ' among which numbers of a species of mites are discovered. When 

 the spider walks, it shakes itself and throws off part of the scales 

 and some of the parasites. 1 



One day I was dissecting a cocoon of Epeira sclopetaria, and had just 

 turned back the white sheeting of the interior sac, thus quite exposing 

 the eggs, when a house fly lit upon the mass, and instantly thrust her 

 proboscis into and sucked out the contents of an egg. I permitted the 

 insect to continue its feast long enough to show that the innumerable com- 

 pany of common flies only require an opportunity to wholly cut off and 

 exterminate their hereditary foes at the very fountain head of life. 

 Spiders themselves enjoy a meal of spiders' eggs ; for example, Staveley 

 speaks of two species of Clubiona feeding upon the eggs of other species. 2 

 Birds have already been alluded to, in the chapter on Aeronautic Habits, 

 as utilizing spider cocoonery in the construction of their nests. Among 



those addicted to this habit are the pewit, 3 the 

 E . wren, 4 and the vireo. I have several specimens 

 of nests made by a species of the last named bird ; 

 probably Vireo noveborocensis, collected in Fairmount Park, 

 in all of which cobwebs have been used more or less freely. 

 (Fig. 339.) I am told that this is habitual with that bird. 

 The texture of the spinningwork shows, evidently, that it 

 had been plucked from cocoons ; and if this were done 

 before abandonment by the brood, at least before hatch- , 

 ing, the destruction of the contents must have followed. FlG- 338, A cocoon 

 It illustrates the catholicity of habit among the animal nest of E P eira > 



... ,...,-, . rifled of its eggs. 



races, that Dr. David Livingstone, the distinguished mis- 

 sionary explorer, found a like habit in Africa among the sunbirds. 5 



Mr. Carl Voelker has a specimen of the nest of a hummingbird, which 

 is composed in considerable part of various portions of spinningwork taken 

 from the snares and cocoons of spiders. He has seen our common red 

 throat hummingbird, Trojilus rubicolis, darting at the webs of spiders 

 and gathering the threads in its bill for nesting purposes. He has also 

 found minute spiders in the throats of birds of this species, and believes, 

 therefore, that it is their habit to feed upon spiders. The Blue Gray Gnat- 

 catchers also use spider webs for the construction of their nests, and thus 

 probably destroy the young in their cocoons. 



1 Cuvier, Animal Kingdom, Ed. Lond., Vol. XIII., Supplement, page 463. 



2 British Spiders, page 101. 



3 Mr. Thomas Meehan, the botanist, is my authority for this statement. 



4 Mrs. Treat, " My Garden Pets." 5 Livingstone's Last Journals, page 453. 



