USE OF THE TIGER BEETLES. 25 



into working order. All carnivorous creatures require a con- 

 stant supply of nourishment. The internal fire fed by animal 

 fuel burns fast and fiercely, so that a Tiger Beetle larva would 

 die of hunger through a temporary deprivation of food which 

 would little affect the turnip grub or the cabbage caterpillar. 



Then, Tiger Beetles cannot exist in cold countries, because 

 they could not obtain the needful supply of insect food. But 

 when, as in the great tropical belts of the world, they find vast 

 tracts of uncultivated land swarming with insect life, it is 

 evident that all the surroundings are favourable to their de- 

 velopment, and that therefore they may be expected to increase 

 and multiply to the very utmost. 



Their mission is evidently twofold. As carnivorous insects, 

 they form part of the "balance-wheel" of creation which has 

 already been mentioned ; and, as burrowing larvae, they aid in 

 developing the power of the soil. Not only do they drill the 

 surface of the earth with their perpendicular tunnels, thus 

 admitting the light, air, and moisture on which the fertility of 

 the soil so much depends, but they leave at the bottom of the 

 burrows the rejected portions of the insects which they have 

 slain and eaten, together with the whole of their own refuse, 

 and therefore manure as well as lighten the ground. Iu culti- 

 vated land both these duties are performed by human labour, 

 and the spade, the fork, and the plough do the work which was 

 formerly left to the Tiger Beetles. The work being done, the 

 Beetles are needless, and so perish from off a soil on which they 

 have no duties to perform. 



Though the indirect services which they render to man are 

 thus evident, their direct services have scarcely been acknow- 

 ledged. Yet there is at least one species which is used by man, 

 though its use is very limited. This is a Mexican species called 

 Cicinclela curvata, which has a way of burrowing in moist sand. 

 The natives have an idea that, like the Cantharis, or " Spanish 

 fly," with which we are all familiar, it possesses medicinal 

 properties, and so they prepare an infusion of the Beetles either 

 in water or spirits. I am not aware that any other species of 

 Tiger Beetle has been in any way utilized by man. 



On seeing a fair collection of these insects, the most super- 

 ficial observer must be struck with their marvellous beauty of 

 form and colour. Even when placed in formal rows in a 



