206 PROTECTION AGAINST INSECTS. 



woods should be avoided, and the area should be isolated 

 by ditches. Beds are sometimes made with walls and bottoms 

 of stones, and filled in with sifted soil. 



vii. Oviposition may be prevented by covering the beds with 

 dead leaves or twigs, or by sprinkling them with flour of 

 sulphur. 



e. Remedied Measures. 



i. The areas to be stocked, in swarm-years, should be 

 completely broken up with the plough, or trenched with spade 

 or hoe, in order to destroy the larvae. This can be done only 

 on fairly level ground. Gas-lime may be ploughed into the 

 land, which must then lie fallow for six months. 



ii. Collection in sacks of the larvae which are turned up in 

 cultivating the ground, from June throughout the summer. 

 This is best undertaken before a swarm-year, as the larvae are 

 then nearest to the surface of the ground. It may be done 

 both in nurseries and before restocking felled areas. 



iii. Collection of the larvae by digging round plants which 

 are attacked in the cultivations ; this can be done throughout 

 the summer. 



iv. The construction of traps for larvae, as follows : 



a. Sods of grass or heather in square pieces measuring 

 8 to 10 in. in breadth are placed with the grass downwards 

 on the cultivations. In the forest of Allstadt, Weimar, in the 

 autumn of 1870, on 7 J acres of ground covered with grass and 

 heather, square grass sods 8 to 10 inches broad and 6 to 8 

 inches thick, were laid on the surface of the ground with the 

 grass downwards, and from 3 to 11 larvae were found under 

 each sod in July, 1871. Thus, in a short time, 16,000 larvae 

 were collected. 



b. Kolls of bark filled with loose soil, and placed in 

 the ground. Successfully done in 150 Prussian ranges in 

 1883-84. 



c. Heaps of turf, weeds, humus, burned sods, and dung. 



Such heaps afford looseness, dryness, warmth, and nourish- 

 ment for the larval development, and Heyer greatly recommends 

 their use in nurseries. The females also readily lay eggs in 



