150 ANIMALS IN THE DARK 



is not the object of fear, but merely marks the time 

 when the object of fear is abroad. Among our 

 domesticated animals in this country the terror is not 

 personified, but the nervousness survives in an im- 

 personal form. It is not often in evidence, and needs 

 some incident to arouse it ; but there is no doubt that 

 the propensity to fear increases with darkness and 

 vanishes at daybreak. 



The effect of darkness on insects shows some striking 

 differences. Butterflies are so sensitive to want of 

 light that they are not only stupid and sleepy at 

 night, but are affected in the daytime by the shadow 

 of every passing cloud. It is a common practice of 

 butterfly-hunters to keep their eye on an insect 

 without pursuing it, waiting till a cloud comes, when 

 it is nearly certain to settle down and become more 

 or less torpid. Possibly it fears rain ; but some moths, 

 whose wings are no less fragile than those of butter- 

 flies, often fly on evenings when a slight rain is 

 falling. Except the owls and the night-jar, most of 

 our night-feeding birds are thoroughly keen-sighted by 

 day. They include the whole class of birds ducks, 

 waders, storks, and herons which feed on the muds 

 left by the tide. It is generally held that these birds 

 can see equally well by night as by day. Very few 

 people have spent enough time out on the muds by 

 night to speak on this point with certainty ; but a 



