Ferguson. — 0>i the Enemies of Young Trout. 235 



always make in this country, that in time, unless great care 

 is taken, we may find the mole-crickets as troublesome as 

 they are in Europe. 



Luckily, there are numerous ways of getting rid of them, 

 and nature helps considerably, for the mother herself frequently 

 eats large numbers of her children. Their sense of smell is 

 very acute, and it has been found a good plan to bury a dead 

 crab in the ground infested by them, or pour water with a little 

 oil or turpentine down their burrows, when those not killed 

 will at once vacate. 



The mole-cricket, though feeding principally upon vegeta- 

 tion, is really omnivorous, and will take raw beef, grubs, &c., 

 with zest. It has been stated that they are really useful 

 because they do this, but the best authorities give them an 

 unqualified condemnation. 



Like their relations, the field-crickets, they are very w^ar- 

 like, and have cannibalistic tendencies, for when an enemy 

 has been vanquished he is sure to be eaten. 



Addendum. — Since this paper was read the author has been 

 informed that Mr. Eobinson, of Makara, near Wellington, is 

 familiar with the mole cricket, but does not think it has in- 

 creased in his district during the last two or three years. 



Aet. XXVII. — On the Cause of the Disaxii^earance of Young 

 Trout from our Streams. 



By Alexandee Ferguson. 



Communicated by T. W. Kirk, F.E.M.S. 



[Eead before the Wellington Philosophical Society, 9th January, 1889.] 



During the past fifteen years trout-fry have frequently been 

 put into the streams in this district (Palmerston North), but, 

 so far as I am aware, they have never been seen afterwards. 

 Some thought they had been devoured by eels, and others 

 that they had been washed out of the streams by freshes. As 

 it is a subject in which I take considerable interest, and one 

 which has cost many a pound to no purpose, I set myself 

 some twelve months ago to discover, if possible, what was 

 really the matter. It occurred to me that there was little use 

 in examining the streams, or in speculating on the cause of the 

 mischief, and that something more practical would require to 



