34 



course of felling, isolated trees or groups of trees well exposed to the 

 sun and with plentiful foliage are left standing. The selected tre^s 

 are of small size, but with a well-developed top. In forests composed 

 exclusively of deciduous trees, the formation of such groups is difficult 

 and partial success is all that can be hoped for. The Bienwald is 

 divided into sections of 741-988 acres, in each of which the work is 

 done by one or more gangs of seven persons. The captured cock- 

 chafers are killed with carbon bisulphide (0-16 oz. of CS2 per gallon of 

 cockchafers) and afterwards used for manure. The number of gangs 

 per section varies according to the quantity of cockchafers. In 1903, 

 15 gangs were used to clear 741 acres; in 1907, 30 for 4,128 acres; in 

 1911, 52 for 4,330 acres ; and in 1915, 42 for 4,330 acres. The success 

 of the work depends on the ability of the man in charge, who must 

 determine the time when operations are to be begun. At the time of 

 flight he must go over his section every evening to ascertain 

 where the cockchafers have settled, in order to make the 

 necessary arrangements for their capture the following morning ; 

 the insects must be gathered at least once a day. In 1907, 15 millions 

 were captured; in 1911, 22 millions; and in 1915, 14 milhons. The 

 increase up to 1911 is due chiefly to the increased area and improved 

 technique of control. Though this method did not entirely free the 

 forest, the insects were so reduced in numbers that it became possible 

 to carry on forestry on the right lines. The larvae cause great havoc 

 in the nurseries, and it was calculated that two larv^ae per 11 square feet, 

 in their third year of development, are sufficient to destroy all the 

 young plants of a nursery. Collecting the cockchafers in the woods 

 around the nurseries is not sufiiciently effective, but when no rain falls 

 during the flight period, excellent results are obtained by covering the 

 soil with quicklime at the rate of 16 cwt. per acre. Rain permits the 

 females to pass through the layer of lime in order to oviposit in the 

 ground. Lime spread immediately after rain is also ineffective and 

 the success of this method therefore depends on the weather. Trials are 

 however beingmade with naphthaline, which is apparently uninfluenced 

 by weather conditions. The control work in the JBienwald was 

 relatively inexpensive, the cost being about 55. Id. per acre in 1907, 

 is. Id. in 1911, and 45. in 1915, while the value of the forest has 

 increased by nearly £4,000 a year as a result. 



LiJSTNER ( — ). Agrotis segetum, Beet and Potato Pest in Germany. — 

 Internat. Rev. Science & Practice Agric, Mthhj. Bull. Agri'^. Infill. 

 & PI. Dis., Rome, vii, no. 6, June 1916, p. 914. [Abstract from 

 Amtsblatt der Landwirtschaftskammer fiir den Regierungsbezirk 

 Wiesbaden u. Zeitschr. des Vereins nassauiscJier Land- u. Forstvnrte, 

 Wiesbaden, 97th year, no. 37, pp. 277-279.] [Received 10th 

 November 1916.] 



During 1915, the larva of Euxoa {Agrotis) segetum caused widespread 

 injury in the beet and potato fields in Germany. This infestation is 

 believed by the author to be abnormal and possibly related to the long 

 period of drought during the spring and summer of 1915, which 

 destroyed the usual food of the larvae. In one locality the larvae 

 diaappeared completely from the potato fields after a fall of rain. 



