Hudson. — On Instinct In Insects. 355 



to be an unexpected application (by the moth) of the theory 

 of natui'al selection, but, as the normal condition of heaths can 

 hardly be that of periodic burning, or can hardly have been so 

 long enough to produce so important a modification in a moth, 

 and as there are very few birds on these heaths, and none 

 equal to inflicting serious damage on so active an insect, I can 

 only suppose that a theory of individual jprefcrcncc is appli- 

 cable in this case. — Chas. G. Barrett, King's Lynn, Norfolk, 

 England. September, 1886." 



In connection with this most interesting observation, I 

 cannot help thinking that, even allowing for the scarcity of 

 the birds, the habit of perching on burnt ground has probably 

 been the result of natural selection. Prior to the burning of 

 heaths no doubt the black coloration was useful to the insect 

 for another purpose — possibly to absorb heat ; but since the 

 alteration in its environment has taken place the colouring 

 has become serviceable for protective purposes. Hence it is 

 probable that if adequate records had been kept we should 

 find that the species had become much more numerous in 

 recent times. 



On the 5th October, 1890, while searching for insects on 

 tree-trunks in the forest near Wellington, I heard an un- 

 usually loud buzzing sound in the neighbourhood. On 

 endeavouring to ascertain the cause, I discovered a small 

 hunting-spider of the grey species (family Salticidae), which 

 frequent sunny tree-trunks, struggling with a large flesh-fly 

 fully four times its own size. The spider had seized its victim 

 by the sternum, but the fly continued violently moving its 

 legs and wings for more than eight minutes. During this 

 time the little spider had considerable difficulty in detaining 

 such a large insect. 



In this case I think the action of the spider in biting its 

 victim in the sternum, which is the seat of the great thoracic 

 nerve-centre, and consequently the most vital part as regards 

 locomotion, was undoubtedly instinctive. I do not imagine 

 any one would contend that the spider had a knowledge of the 

 internal anatomy of its victim, or that it acted through in- 

 dividual experience. The obvious explanation is inherited 

 instinct, or the experience of the race accumulated during 

 countless generations by natural selection, preserving those 

 individual spiders which were most successful in killing their 

 prey. 



On the 1st February of the present year I was collecting 

 and observing insects in the same locality. Whilst approach- 

 ing a mass of dead branches which was situated near the 

 track I observed what appeared to be a leaf fall from one of 

 the upper twigs, stop for a second on another twig, and finally 

 come to rest on the ground amongst a lot of litter. I felt 



