334 



trees banded, some 35,000 larvae would have been the progeny of the 

 larvae caught by the bands and destroyed. During the three years of 

 weekly banding, it is calculated that about £31 10s. worth of apples 

 were saved at a total cost, for bands and labour, of £3 10s. 



It was found that there were four overlapping generations of the 

 moth, indicating a different length of life-cycle in dift'erent individuals. 

 The first larvae were caught on 18th May, with maximum numbers in 

 July and August. Natural enemies observed during these investiga- 

 tions were the larvae of a Clerid beetle, which seem to attack those of 

 C. jpomonella chiefly while they are in shelter or during pupation in 

 such places as under bark or bands. Lace-wing larvae do not attack 

 the codling moth so much under the bands as in the open. Small 

 red ants destroy a good many larvae, especially under bands and 

 other shelters, and birds, pigs and chickens all prey upon them. 



Ball (E. D.) & Walter (E. V.). Injury from White Grubs in Iowa. — 



^ Iowa Agric. Expt. Sia., Ames, Circ. no. 60, [n.d.] 4 pp., 2 figs. 

 [Received 3rd June 1919.] 



During the past ten years there have been serious Ipcal infestations 

 of white grubs [Lachnosterna] in north-eastern Iowa, which are part 

 of a general outbreak appearing in a number of more or less timbered 

 areas in a belt running from Minnesota and Iowa east to New York, 

 Connecticut and New Jersey. The grubs first appeared in unusual 

 numbers in 1909, increased in 1912 and were most abundant in 1915. 

 The 1918 outbreak was less severe, and it is probable that parasites 

 and other enemies of the grubs will reduce them to nearly normal 

 numbers in 1921 or 1924 at the latest. A map shows the areas that 

 have been most severely affected. It is observed that bad infestations 

 seldom occur very far from timber. The grubs are found under 

 natural conditions only in grass sod, and never travel from one field 

 to another. When grass land infested with them is ploughed up and 

 used for other crops, the grubs are compelled to feed upon whatever 

 they find there. Maize and potatoes suffer most in this way. Small 

 grains are seldom much injured owing to their abundant root-system 

 and early maturity. The life-cycle of these beetles is described 

 and illustrated. Proper crop rotation and autunm ploughing of 

 infested land are the best measures against increase, and the steps 

 to be taken are forecasted for the ensuing years. It is known that the 

 large grubs will come to the surface in the springs of 1919 and 1922 

 and feed greedily for a short time before they pupate. All sod land 

 intended for cultivation during the next two years should be broken 

 in the autumn of 1919 or the spring of 1920 before the adult beetles 

 emerge. During 1920 and 1923 adults will appear and may defoliate 

 trees but will not injure crops. Small grain should not be planted on 

 land intended for maize in the following year. Lucerne or clover may 

 be broken up in the autumn for maize growing. In 1921 and 1924 

 maize should not be planted on land that was in grass or grain the 

 previous year if young grubs were present in the early autumn. An 

 infested maize-field might be planted with buckwheat, beans or peas, 

 or possibly millet or sugar-cane if the grubs are not too^abundant. 



