499 



complete its life-c}-cle iii three years, and M. hippocastani in four. 

 In certain districts, as for instance along the Rhine near Arnheni- 

 Wageningen, so-called May-beetle seasons occur every three years. 

 Ritzema Bos^ is of opinion that the large numbers of beetles constituting 

 an outbreak have a numerous progeny, which however only appear 

 three years later. Though there are still many beetles to be seen 

 in the year following an outbreak, their newly hatched larvae are 

 handicapped by the presence, in enormous numbers, of strong, one- 

 year-old larvae descended from the adults of the outbreak year, and 

 most of them finally succumb to the resultant unfavourable conditions. 

 Oudemans also refers to the camiibalism of the larvae, by which the 

 younger individuals fall victims to older and stronger ones. This would 

 naturally tend tO conserve a difference in numbers that has once been 

 established. Ampliimallus solstitialis occurs in the eastern provinces, 

 the adult feeding on the leaves of various deciduous trees and on 

 pine needles of the preceding year. The larva attacks grass roots 

 and also injures rye. Pohjphylla fvllo is usually found in sandy 

 neighbourhoods, especially on the North Sea dunes. If feeds on the 

 young pine needles, as well as on those that are one year old, and also 

 attacks deciduous trees. Its larva feeds on grass roots and severely 

 injures the beach grass largely gro^^^^ to protect the dunes. The 

 roots of pine. Rohinia pseudacacia and birch also suffer, and young 

 trees may be killed. Collection appears to be the only met.hod of 

 checking this beetle. Phyllopertha horticola, occurs in the drier districts 

 and appears above ground towards the end of ^lay and early in July. 

 It feeds on the foliage of oak, beech and other deciduous trees, on 

 young apple and pear fruits^ and the stamens, pistils and buds of the 

 rose. The larva feeds on the roots of grasses, the life-cycle occupying 

 one year. Remedial measures include jarring the plants, which must 

 be done early in the morning, and spraying with a poison such as 

 lead arsenate or Paris green, mixed at the rate of 1 per cent, in a I per 

 cent, solution of milk of lime. 



Stieltjes (D.). De Bestrijding van Aardvlooien. [Measures for 

 combating Flea-Beetles.] jTi^'rfi-cAr. Plantenziekten, Wagenitigen, 

 xxiv, no. 4, July 1918 ; Bijblad, pp. 43-44. [Received 3rd 

 September 1918.] 



About 1910 the author began some experiments with trap-plants for 

 flea-beetles and this method has continued to prove successful. 

 Lepidium sativum was chosen for the purpose and was planted between 

 rows of cabbages of different kinds. Other growers who tried this 

 plan also reported very favourably upon it. L. sativum grows rapidly, 

 so that the beetles are quickly attracted ; it need not be feared as a 

 weed, and its seed is cheap. 



Maarschalk (H. ). Musschen en Appelbloesemkevers. [Sparrows and 

 Anthonomus pomorum.] — Tijdschr. Plantenziekten, Wageningen, 

 xxiv, no. 4, July 1918 ; Bijblad pp. 45-46. [Received 3rd 

 September 1918.] 



This note points out that sparrows are not without their uses in 

 orchards, for they have been seen to search for and destroy the larvae 

 of Anthonomus pomorum infesting apple trees. 



