THE FOREST NURSERY 347 



time, usually early in the morning or late in the afternoon. Mice 

 are strictly nocturnal in their feeding habits. When the seed- 

 beds are sown in the spring the period of damage is seldom longer 

 than from 3 to 6 weeks. If germination is irregular and some 

 of the viable seeds are slow to germinate, the damage may 

 continue all summer and is not confined to the loss of seed 

 but also includes the loss of young seedlings destroyed in digging 

 up the seed. Autumn-sown seedbeds are subjected to a much 

 longer period of damage. The beds in rodent-infested regions 

 should be closely watched for evidences of damage, which are 

 usually most apparent in the early morning. The degree of dam- 

 age is expressed by the number of fresh holes in the seedbeds 

 and by the quantity of seed-coverings scattered over the surface. 

 Whenever evidences of damage appear measures should be im- 

 mediately taken to prevent serious losses. 



All measures undertaken in forest nurseries to prevent the 

 destruction of seed by rodents relate to the following: 



a. Measures taken to prevent the rodents from reaching the 

 seedbeds. 



b. Measures taken to destroy the rodents. 



The first effort in control should be directed toward keeping 

 the nursery and its surroundings free from rubbish and other 

 material that may afford nesting places and retreats for rodents. 

 Rodents have been effectively excluded from many nurseries by 

 screening against them. Thus, at the Pocatello nursery the lath 

 house in which the seedbeds are formed is enclosed by closely- 

 woven wire screens about 2 feet high and partially embedded in 

 the soil. The ordinary seedbed box provides an effective barrier 

 against squirrels and chipmunks. 



When rodents occur in destructive numbers in large nurseries 

 the damage can usually be greatly reduced or entirely eliminated 

 by systematic methods of destruction. When once destroyed 

 over the nursery and adjacent areas they seldom become trouble- 

 some in later years. They are most effectively reduced by sys- 

 tematic trapping or poisoning. The same methods should be used 

 in the nursery that are practiced in freeing a site from rodents 

 preliminary to direct seeding. 



Moles are troublesome in many nurseries, due to the numerous 

 tunnels made by them and the drying out of the soil above the 

 tunnels. The benefit derived, however, is often more than the 



