226 



THE YOUNG 



NATURALIST. 



found dead than any other species. Moles 

 living below the surface may come out to 

 die, but they are so easily killed that it may 

 be those found dead have met with some 

 slight accident. Both Moles and Shrews 

 are so often found dead on paths and walks 

 that popular superstition has been called in 

 to account for it. The place or manner of 

 their death, however, has but little to do 

 with the question of their longevity, and it 

 does not appear that the rarity with which the 

 dead bodies of other species are met with is 

 an important factor either. Most of our wild 

 mammals are but seldom seen alive, not 

 because they are few in number, but because 

 we have made ourselves their enemy and 

 they seek concealment from us, as much as 

 from those animals that prey upon them. 



Migratory birds have an additional peril 

 to those already named. We once saw our 

 beach strewn with dead bodies of hundreds 

 of the Norway Crow just as those birds had 

 left our shores. A heavy north-easterly 

 gale had come on before they had got far 

 away. Some of them would doubtless strug" 

 gle through it, but large numbers had per- 

 ished so near the shore that, instead of being 

 devoured by fish or crustaceans, they washed 

 up on the beach. The gale that destroyed 

 so many of these strong-flying birds would 

 be still more fatal to smaller species. Birds 

 appear to have considerable foreknowledge 

 of the weather, and will not generally start 

 on their migration when a storm is near. 

 That referred to above must have given 

 little warning of its approach. But even 

 with favourable weather hundreds and thou- 

 sands of birds must perish in their annual 

 migrations, tending thus to reduce the aver- 

 age duration of life, and to increase the 

 necessity for the longevity of some to keep 

 up the race. 



Our knowledge of the duration of animal 

 life is but in its infancy, but much more will 

 be known at the end of another hundred 

 years. It is, however, worth our while to 



make such effort as is in our power to add 

 to what is known. Only one theory has 

 been advanced on the subject, viz., that the 

 duration of life depends in some proportion 

 on the length of the period of gestation or 

 the time the species needs to attain maturity. 

 It does not appear that this is borne out by 

 the facts, though it may be found to be of 

 some importance when the subject is better 

 understood. 



HELPS AND HINTS FOR 



YOUNG ENTOMOLOGISTS. 



By Albert H. Waters, B.A. 



September Butterflies. 

 The number of species of butterflies is 

 now very much diminished, yet a few still 

 remain— the Red Admiral ( Vanessa atalant a) , 

 with its scarlet bands, the Peacock ( Vanessa 

 Io), with its four beautiful spots or " eyes," 

 the Painted Lady (Vanessa car dm) t with 

 her delicately tinted pinions, and the abun- 

 dant, yet handsome, Tortoiseshell ( Vanessa 

 urticce), all attend on Ceres as she comes 

 in the procession of the year. And not only 

 these, but there are the rare Camberwell 

 Beauty (Vanessa antiopa), and the Queen of 

 Spain Fritillary (Argynnis lathonia) to be 

 still looked out for. And you should look 

 out now for the larvae of the Clouded 

 Yellow and Wood White butterflies if you 

 are living in, or visiting the South of England. 

 The caterpillar of Colias edusa is green with 

 minute black warts, and a narrow white 

 stripe on each side of the body ; the spiracles 

 are yellow. It feeds on clover. That of 

 Leucqphasia sinapis is of a beautiful green 

 colour with the front segments minutely 

 dotted with black, and with a yellow 

 spiracular line edged above the darker 

 green; it feeds on tufted vetch (ficia 



