well distributed over the State and often appears unaided in an in- 

 festation of cottony cushion scale (Icerya purchasi), yet in 

 many cases it does not occur, and neither does the scale become very 

 abundant. The chccking of the scale in such cases must be accountet 

 for through some other factors. Sometimes, too, the beetle is slow in 

 getting the scale under control. On the Station grounds at Riverside 

 fifty or seventy-five orange trees have been infested witli the cottony 

 cushion scale, as bad as occured when the insect was at its height, 

 for at least four years. During this time also the ladybird beetle 

 has been prescnt. The scale becomes very abundant each spring, when 

 the c a r d i n a 1 i s begins work and effcctivcly checks theni. The 

 beetles are present in April, May and June and disappear in July. 

 Some young scales are left and those have a chance to multiply and 

 severely infest the tree again before the c a r d i n a 1 i s appears in 

 the spring. This has been the history of the infestation for the past 

 four years." 



Nach diesem Bericht, der erkennen läßt, daß Icerya selbst in 

 Californien keineswegs durch den Novius zur Seltenheit geworden, 

 geschweige denn ausgerottet ist, ist allerdings einige Skepsis am 

 Platze, ob man mit der bisherigen Bekämpfungsmethode allein aus- 

 kommt. Füller, der Regierungsentomologe von Natal in Süd- 

 afrika, ist davon allerdings überzeugt. Er schreibt: 



,,In view of the fact that nowadays the bug and its ennemy are 

 so rare it seems a pity to destroy the former because it amounts to 

 cutting off the sparse foot-supplies of the beetle. In every case which 

 has come under my Observation the \"edalia had put in on appearence 

 sooner or later and destroyed the scale, and consequently its attack 

 need never be regarded with any alarm. If it seems very essential 

 to remove the bug from infested plants, then the best plan is to set 

 a native boy to cleaning it oft', cutting out and burning badly infested 

 portions. Before such a course is taken, however, a search should 

 be made to see if the ladybird is present, and if so, than on no 

 account should the bug be destroyed." 



Es ist natürlich schwer, ohne die Wirkungen der natürlichen 

 Bekämpfungsmethode mit eigenen Augen gesehen zu haben, ledig- 

 lich vom grünen Tisch aus ein Urteil über die Möglichkeit des Er- 

 folges abzugeben. Immerhin ist gerade der Fall, welcher für Icerya 

 purchasi vorliegt, der theoretisch am meisten cinleuchteinde, daß 

 durch Einschleppung eines Schädlings ohne seine Feinde das natür- 

 liche Gleichgewicht gestört und durch die nachträgliche Einbürge- 

 rung dieser Feinde aus dem Hcimatlande des Schädlings wicderher- 



Tropenpflanzer 1913, Heft 6. 2^ 



