532 



of the crop is not in itself sufficient to induce infestation by frog- 

 hoppers, the prevalence of which is apparently governed by relations 

 between soil and moisture that are not yet understood. The prevalence 

 of root disease over wide areas in Trinidad is largely due to the 

 weakening of the plants" resistance as a result of froghopper attack. 



No direct method for controlling this pest has yet been found. 

 [R.A.E., A, vii, 336.] 



NowELL (W.). Report on a Visit to Trinidad in connexion with 

 Froghopper Blight of Sugar Cane. — B^dl. Dept. Agric. Trinidad dc 

 Tobago, Port-qf -Spain, xix, part 1, 1920, pp. 11-18. 



The observations made during 1919 do not at any point conflict 

 with the opinions expressed in the j^revious report [R.A.E., A, vii, 

 335], the results being summarised in the preceding paper. 



Wilson (H. F.), Pickett (R. C.) & Gentner (L. G.). The Common 

 Cabbage Worm in Wisconsin {Pontia rapae, Linn.) — Wisconsin 

 Agric. Expt. Sta., Madison, Research Bull. 45, August 1919, 35 pp., 

 11 figs. [Received 19th October 1920.] 



As a result of extensive investigations made during 1916 & 1917, 

 the various stages and life-history of Pieris {Pontia) rapae are described. 

 Lead arsenate and calcium arsenate have proved to be the most 

 effective remedial measures and are not injurious to plants [R.A.E., 

 A, vi, 201]. Pteromalus puparum, L., and Apanteles glomeratus, L., are 

 parasites of this butterfly in Wisconsin. 



Fluke (C. L.), Junr. The Pea Moth : How to Control it. — Wisconsin 

 Agric. Expt. Sta., Madison, Bull. 310, April 1920, 12 pp., 9 figs. 

 [Received 19th October 1920.] 



The pea moth, Cydia (Laspeyresia) nigricana, Steph., is recorded 

 from Michigan and the north-eastern counties of Wisconsin. The 

 various stages are described. The moths appear shortly after the pea 

 vines begin to bloom. The eggs are generally laid singly on pods, 

 leaves and stems of the plants, and even on weeds and grasses in their 

 vicinity. The first eggs were noticed on 17th July ; these hatch in 

 from 7 to 10 days. The larvae eat their way through the pods and 

 feed on the peas. They mature in from 16 to 26 days, and when full 

 grown, enter the ground or hide in any suitable place such as cracks 

 or crevices in the barn. Hibernation occurs in this stage, foUowed 

 by pupation in the spring. 



The remedial measures advocated include deep autumn ploughing 

 and thorough disking of the soil after the peas are harvested. The 

 peas should be thrashed within a day or two after harvesting. Unless 

 the remaining straw is used as fodder it should be destroyed by 

 burning. Infestation may be avoided to a certain extent by planting 

 early maturing varieties of peas as early in the spring as possible. 



A footnote by C. Heinrich states that the insect here referred to as 

 C. (L.) 7iigricana, Steph., is distinct from the European species. The 

 possibility of a native as well as the European species infesting peas 

 in the United States is therefore suggested. 



