I060 INSECTS ETC. INJURIOUS TO VARIOUS CROPS 



these parasites a piece o| cane must, before planting, be steeped in a solu- 

 tion of calcium sulphide of 3" Bcaume strength or a 2 % emulsion of soap 

 and kerosene, for 15 minutes. 



534 - The Leopard moth (Zeuzera pyrina), a Dangerous Imported Insect Enemy 

 of Shade Trees in the United States.— Howard X,. O. and Chittenden I". H. in Lnited 



States Department of Ai^riculture. I'nrmer's Bulletin 708, pp. i-io. Fig. 1--1. Washington, 

 D. C. February i-(, igi6. 



In the Hudson Valle}' and on the Atlantic seaboard, from Massachusetts 

 to New Jersey, shade and ornamental trees and shrubs of many kinds, 

 with the exception of evergreens, are severely injured by the larvae of the 

 lepidopteron Zeuzera pyrina Fab. (Z. aesculi L-, Z. decipiens Kirby), a 

 European species accidentally introduced a short time since in the United 

 States. 



These larvae mine long tunnels in the living wood and stop growth to 

 such an extent as to cause the death of the plant, especially in young trees. 



In any case the presence of these tunnels weakens the trees, so that they 

 are less able to withstand wind presc5ure, and also opens a path for other 

 insects or germs of the most varied diseases. 



The trees attacked are not onh^ the horse chestnut, chestnut, walnut, 

 oak, maple, alder, birch etc., but also fruit trees, such as pear, apple and 

 plum trees, etc. 



Some birds and mammals are among the most effective natural ene- 

 mies of these insects. 



Artificial means of control ; i) cutting and destro^dng the infested wood; 

 2) injecting carbon disulphide into the tunnels bored and afterwards block- 

 ing up the apertures very carefully ; 3) lighting very bright fires in those parts 

 where the insects abound ; the pests will be attracted by the light and fall 

 into specially arranged pans filled with water and petroleum. 



535 - Pseudococcus citri, P. bakeri, P. citrophilus and P. longispinus 



in the Citrus Plantations of Southern California. — Clausen Curtis p. in Agricultural 



Experiment Station, Berkeley, Ccilifornia, Bulletin Xix 258, pj). i--iS, 8 Fig. Berkeley, 1916. 



Four species of Psetidococcus : P. citri Risso, P. bakeri Essig, P. citro- 

 philus Clausen Mss. and P. longispinns Targ. are particularly injurious 

 to citrus trees in vSouthern California, especiall}' in the seaboard region, where 

 the moisture and heat conditions favour their growth. On the other hand 

 the outbreaks become more and more sporadic and rare in the interior. 



(i) P. citri Risso. — First reported in 1880 in the county of San Diego 

 whence later on it spread into the countries of Orange, Los Angeles, Ventura 

 and Santa-Barbara . Owing to the considerable quantity of the juices which the 

 adults take from the young branches and fruits, many leaves fall, and the 

 fruits discolour and are very tardy in growth. At the time of flowering, 

 the insect frequently causes fall of the leaves and the barely set fruit. The 

 larvae likewise occasion extensive havoc. The}-^ extract the sap and chloro- 

 ph\'ill from the leaf cells and secrete a large quantity of honeydew, thus occa- 

 sioning the appearance of a rich cryptogamic vegetation {Meliola Caniel- 

 liae) The latter clogs up the apertures of the stomata, which hinders the 

 functions of the leaves. 



