No abstract

There are many records of injury to grassland caused by caterpillars of the genus Cr.ambur in Canada and the United States, where they are known commonly as 'sod webworms'. Such attacks however are not confined to grasses; cereal crops and tobacco frequently show marked injury following the ploughing of infested grassland. Attacks take place every year, but the degree of injury varies from season to season and in certain years attacks of abnormal severity occur : I 93 I was reported from many parts of North America as being a particularly bad year for these pests and injury was widespread and severe. Noble (193a) states that twelve species of crambids are of economic importance in North America and all of these have similar habits. The relative prevalence of these species varies from season to season and in different parts of the country, and it appears to be usual in cases of severe grassland injury for more than one species to be involved in the attack.Hitherto crambid moths, although extremely common, have not been regarded as of much economic significance in this country. During the autumn of 1941, however, a number of instances of injury to grassland in Yorkshire by caterpillars of these moths were brought to the notice of the writer. Larvae taken from these centres of attack were reared and, so far, d adults obtained belong to the species CImnbtrr horhrcuUr Hb. This moth is one of the common species of economic importance in North America but is not regarded there as being one of the most hannful species. Injury was first reported at the beginning of October 1941. The areas affected were in the vicinity of Reeth in Swaledale and one isolated Wes! Riding centre at Northowram, near Halifax. At the latter centre, severe injury was restricted to one field but there was evidence of lesser attack on adjacent fields. NATURE AND EXTENT OF INJURYFields attacked were first visited on 17 Oct. by which time injury showed as large dead patches on the grassland, varying from several acres to as little as a quarter of an acre in extent. On these patches almost every plant had been eaten off at ground level, the herbage lying dead upon the surface of the soil (Pl. IS, fig. I). When the dead grass was moved aside numerous caterpillarsf were exposed amongst the stem bases of the plants. Closer examination also revealed the presence of many silken COCOOI~S, outwardly covered with particles and plant fibre (PI. IS, fig. 2) which made them very difficult to see. These m n s , like the caterpillars, were amongst the bases of the plants either upon the soil surface or lightly embedded in it; they contained caterpillars which at this date had not pupated. In some of the fields, attacked areas were very clearly dehed, in others the injury was more general, though there were always patches more heady attacked than the remainder of the field, the general effect being rather like a moth-eaten V t .' Mr H. M. Edelsten examined the caterpillars and kindly provided the fok-d-dption: cdo\n t-slucent whitish ochreous, with a gmuisb tinge. ...

Summary. The good effects obtained by capturing the beetles when they are swarming on bracken last apparently for several years. A form of trap is described, suitable for capturing them when they are resting on the fronds.

1. Methods of controlling ants invading houses are discussed.2. Various methods have been tried, particularly against Monomorium pharaonis. The more general methods in use such as syrup baiting and the use of various insecticidal powders and sprays show at best a palliative effect and do not exterminate the pest. Destruction of the nest is effective where it can be carried out.3. The use of a thallium sulphate-syrup as a poison bait devised by Popenoe has been tried with success against M. pharaonis and A. (Donisthorpea) niger. This inexpensive method is likely to prove useful in places where it is not practicable to find and destroy the nest, which invariably involves considerable structural alterations.

vitamins, organized by the Vitamin B Committee of Japan, which wa.s attended by about fifty people. This is, of course, a field of intense J apa.nese activity, and some good Japanese papers were presented.