THE HEATHER BEETLE 423 



best in a mild climate with a high average rainfall ; but it is curious to note 

 that after a very wet winter the beetles are not so numerous as after a dry one. 



With regard to the position of the ground affected there does not appear to be 

 any rule, for the extracts show the damage to be done on slopes which face all 

 points of the compass from north-west' through west to south-east. Again, the age 

 of the heather liable to attack appears to vary, for while two correspondents report 

 that young heather is chiefly affected (h and bb), other two note the damage as 

 done to the plants of from four to six years old and upwards (/and ee). Most of 

 the damaged heather occurs in patches, although these may extend over a large 

 area, and there is a certain amount of evidence that low-lying wet, mossy ground 

 is most subject to attack. This may indeed well be the case, for the beetle 

 requires a good deal of moisture during the period of its metamorphosis from 

 larva to mature insect, and during the course of my breeding experiments any 

 pupae which were allowed to become dry failed to develop properly. 



Taking, then, the whole of the evidence into consideration, I am strongly of 

 opinion that the condition k^iown as " frosted " heather is entirely due to the 

 attack of the heather beetle. Indeed, during the course of my experiments 

 a patch of heather kept during the winter of 1908-1909 in a breeding cage in 

 a warm room was eaten by a number of mature beetles kept in confinement. 

 The condition of the shoots, after being nibbled, was undistinguishable in appear- 

 ance from some of the samples sent in by correspondents for examination, and 

 in this case frost was, of course, entirely out of the question. This experience 

 is additionally interesting as proving that the mature beetle, as well as the 

 grub, feeds upon the leaves. 



The question of remedy alone remains for consideration ; but this is a matter 

 which presents some difficulty. It is obviously impossible to use any of the 

 ordinary insecticides, as almost any chemical substance sufficiently poisonous 

 to kill the grub or beetle would be very deleterious or even dangerous to the 

 Grouse, to say nothing of sheep. The great extent of the area to be dealt with 

 in most cases of attack is also a serious deterrent to the use of spraying mixtures. 



Extensive draining of damp, mossy flats might be indirectly beneficial as a 

 preventative of beetles, and would be directly beneficial to the moor in other 

 respects. But draining is an expensive business, and except in districts where 

 the ground can carry a heavy stock of Grouse, or is valuable for pasture, it may 

 be better policy to allow the low-lying flats to remain in a water-logged condition. 

 Another remedy that suggests itself as, at any rate worth trying, is the 



