269 



R^GNiER (R.) . La Station Entomologique de Rouen. — Ann. Epiphyties. 

 Paris, vii (1919 & 1920), 1921, pp. 371-376, 4 figs. [Received 

 15th March 1922.] 



During the period under review, a fresh Station has been added to 

 the Service des Epiphyties, situated at Rouen. This will replace the 

 Laboratory of Agricultural Entomology, directed by the late Paul 

 Noel. A brief review of the work done by this Laboratory during the 

 thirty years of its existence is given, with a description of various traps 

 designed for the capture of insects that have been used with success. 



Ri^GNiER (R.). Un Ennemi du Peuplier: Idiocems populi (Linn6) 

 Flor (Homop.) ou Cicadelle du Peuplier. — Ann. Epiphyties, Paris, 

 vii (1919 & 1920), 1921, pp. 377-385, 10 figs. [Received 

 15th March 1922.] 



The leaf- hopper, Idiocerus populi, L., has been the subject of study 

 during recent years, as it has done considerable damage to poplars, 

 which are among the most valuable trees in France. All stages of 

 the insect are described. The eggs are deposited during the summer 

 in a slit made by the female that penetrates to the pith of the lateral 

 branches of the current year's growth. The eggs rarely number 

 more than five and remain in hibernation until April, when the nymphs 

 appear and subsist at first on the gum exuding from the leaf-buds. 

 In later stages they suck the sap from the leaves, causing them to 

 wilt, and finally attack the stems. Adults appear about six weeks 

 after the hatching of the eggs, generally about the end of May. They 

 are frequently found on grasses, as well as on the trees ; they choose 

 for preference young trees at the edges of nurseries or new plantations, 

 moving from tree to tree but seldom passing from one plantation to 

 another. 



Besides their direct attack on the trees, these leaf-hoppers are even 

 more dangerous as potential disseminators of the bacterial canker 

 caused by Micrococcus populi. Whether the leaf-hoppers actually 

 inoculate the disease into a healthy tree after feeding upon an infected 

 one is not yet known, but the slits made by the female for oviposition 

 cause a gummy secretion at the wound, in which M. populi finds a very 

 favourable medium for development. 



As the chief point of attack of Idiocerus populi is the lateral branches, 

 a very simple method of destroying the insect is to lop off these, and, 

 as this is done in the winter, the branches need not even be burnt, 

 but can be tied up in bundles and left to dry, when the eggs will be 

 destroyed by desiccation of the tissues. Birds, spiders, and an uniden- 

 tified Acarid that has been found attached to the thorax of /. populi, 

 reduce the numbers of leaf-hoppers considerably. Hymenopterous 

 parasites were obtained in rearing cages, which are evidently Mymarids 

 of the genus Gonatocerus and are closely allied to G. maga, Gir. 



/. scurra, found also on poplar, has a very similar life-history to 

 that of /. poptili. 



RitGNiER (R). La Question des Corbeaux en Normandie.— y4«n. 



Epiphyties, Paris, vii (1919 & 1920), 1921, pp. 386-390. [Received 

 15th March 1922.] 



Crows and rooks have been increasing in Normandy to an alarming 

 extent during the last few years, largely, it is thought, owing to con- 

 ditions during the war. Although these birds are of some benefit in 



