Sugar Beet Root-louse Sugar Beet Nematode 



NATURAL ENEMIES 



While in the galls a bug* (Fig. 14, Plate II, Page 13) preys upon 

 the lice. In the beet fields the little lady-beetle l l and its larva (Figs. 

 10 and 15, Plate II, Page 13) feed upon the root-lice. This larva, 

 which is not very much larger than a good sized louse, secretes a white, 

 waxy substance with which its body is covered, making it resemble to 

 a remarkable degree one of the lice upon which it feeds. The pupa of 

 this beetle (Fig. 14, Plate VII, Page 23) is surrounded by the cast larval 

 skin and white flocculent coating. 



The larvae or maggots of the Syrphus-fly 14 (Fig. 13, Plate VI, Page 

 21) do their part in destroying this pest. 



Every season large numbers of the lice are killed by a fungous dis- 

 ease.** This fungus develops within the lice and finally causes their 

 death. Were it not for these natural checks the damage caused an- 

 nually by the beet root-louse would be far greater than it is now. 



Slender, yellowish-white maggots are often seen among the lice on 

 beet roots. These are the larvae of a small, striped flyj (Fig. 14, Plate 

 VI, Page 21). Recent investigations f show that these maggots are 

 very effective in destroying the beet root-lice. During the latter part 

 of the season small, oval, brown bodies will be seen among the lice also. 

 These have often been mistaken for the eggs from which the lice hatch. 

 Instead of being root-louse eggs they are the thickened larval skins 

 within which the maggots change into the flies mentioned above. 



2. SUGAR BEET NEMATODE 



(Figs. 8, 9 and 10, Plate III, Page 15) 



Quite early in the history of the beet sugar industry in Europe it 

 was noticed that the yield of sugar beets was steadily dropping off in 

 certain districts. In spite of the efforts of the growers to maintain the 

 yield by using fertilizers, and in spite of their increasing knowledge of 

 the handling of the crop, the tonnage secured was so unsatisfactory that 

 the growing of sugar beets was discontinued on many fields. 



Many theories were advanced in explanation of this condition. The 

 most prevalent and generally accepted of these attributed the trouble 

 to an exhaustion of the mineral plant foods of the soil. 



It was noticed that those fields where beets had been grown con- 

 tinuously for several years were most affected. This led the Germans to 

 give the name "Riibenmiidigkeit, "or "beet weariness, " to this malady. 



A German scientist named Klihn was first to associate the soil in- 

 habiting eel worm or nematode (Heterodera schachtii) with this trouble. 



The sugar beet nematode so far has been found only in a few well 

 defined localities within the territory in which The Great Western Sugar 

 Company operates. 



*Authocoris melanocerus. 

 **Emt>usa aphidis. 

 IChlorobisca glabra. 



tJ. R. Parker, "Life History and Habits of Chlorofiisca glabia Meign.." Journal of Economic Ento- 

 mology, Vol. XI, No. 4 (1918). ' 

 ("-) See explanation of "Reference Figures." page 2. 



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