DAMAGE CAUSED BY ANIMALS. 191 



for cockchafer grubs, worms, &c., it certainly destroys many seed- 

 lings in nurseries, in the formation of its runs underground ; 

 these at last become as large as could be formed by inserting a 

 finger, for it bites through all roots that oppose its passage, and 

 thus causes seedlings and transplants to wither and die off. This 

 damage may at times become very considerable, especially in 

 Pine and Spruce seed-beds. 



The methods of endeavouring to exterminate the mole-cricket 

 comprise the following : 



The seeking out of nests, which may be tracked by the con- 

 fluence or converging of the runs, that dip down lower into the 

 ground when they approach the nest. Although the runs are 

 marked by air-holes in the soil, which look as if they had been 

 made by sticking one's finger into the ground, and by the wither- 

 ing and dying off of the seedlings, yet it is by no means alto- 

 gether an easy matter to find out the nests. 



The planting-out of ordinary flower-pots, the holes in the bottom 

 of which have been plugged up with cork, about six feet apart, and 

 the stretching of pieces of wood, like laths, across from pot to pot, 

 so that when the crickets are wandering about after nightfall during 

 the pairing-time they cannot pass, but are forced to go along the 

 edge of the lath, and finally tumble into the pots. 



The killing of the mole- crickets when they are calling to each 

 other during the pairing-time. This can be done by cautiously 

 approaching the place where the chirping is noted, and then 

 suddenly dislodging the insect in a clod by means of a hoe. 



The pouring of a tea-spoonful of petroleum, oil, or tar into the 

 freshly-formed runs, which are easily distinguishable after rain, 

 and then pouring in water until the runs are full. As soon as 

 the cricket gets touched by any of the oil, it at once ascends for 

 fresh air, and then can be easily destroyed. 



(b.) INSECTS ON BROAD-LEAVED TREES. 

 I. BEETLES OR CHAFERS (Coleoptera). 



BARK-BEETLES (Scolytidte). 



92. The broad-leaved species are much less exposed than 

 conifers to injuries from bark-beetles, and when the former are 



