481 



leaf hopper) are reviewed. There is one generation a year and the 

 adult, which hibernates, flies to beet fields in late spring and lays eggs 

 in beet stems until mid-summer. The larvae mature in summer 

 and the adults disappear in early autumn. E. tenella is a native 

 insect inhabiting the south-western United States and northern 

 Mexico and extending into the Columbia River region, whence it 

 spreads for hundreds of miles in years of bad infestation. It is found 

 on shadscale {Atriplex confertifolia), grease wood {Sarcobatus), Russian 

 thistle [Salsola], and fine-leaved annual salt-bushes [see this Review, 

 Ser. A, vi, p. 418]. Its original food-plant is unknown. Apparently 

 swarms of the insects from wild plants fly from their breeding grounds 

 for long distances and over mountain barriers. 



Investigations into the method of transmission of the disease have 

 aheady been noticed [see this Review, Ser. A, v, p. 492]. Factors 

 favourable to curly-leaf development are the presence of large numbers 

 of E. tenella, early attack, hot weather and clean cultivation, which 

 results in the elimination of shade for the beets ; the converse of 

 these factors, together with frequent cultivation, early irrigation 

 and shade or weeds are unfavourable to the disease. (Growing for 

 seed is very uncertain in curly-leaf areas. 



Destruction of the hoppers should be eifected by pulling a drag over 

 the leaves of the beets and directing a spray at the plants at the 

 moment the hoppers jump to avoid it. The spray should be a 15 per 

 cent, kerosene emulsion. Early planting, which in California is 

 carried out in November and December, eliminates injury to a large 

 extent. Thinning should not be done just when the hoppers are 

 appearing ; a knowledge of conditions of the breeding-grounds is 

 useful in predicting possible outbreaks. Parasites of E. tenella, to be 

 effective, should be introduced into the permanent breeding grounds. 

 The outlook in certain regions is serious, and it is estimated that during 

 the years 1899-1915 there was a direct loss of £2,000,000 in the United 

 States due to this insect. 



Sanders (J. G.). Corn Root Aphids Active. — Wkly. Press Bull. 

 Pennsylvania Dept. Agric, Hartisburg, iii, no. 33, 15th August 

 1918. 



During July and August many complamts were received from 

 various parts of Pennsylvania of the damage to maize by the corn 

 root aphis [Aphis maidiradicis], which is carefully fostered during 

 the winter in the nests of the brown ant. The only satisfactory 

 method of clearing land of this pest is rotation of crops. Maize 

 planted in iufested land will have very little chance, but if planted 

 in clean land it will have had such a good start by the time the ants 

 have deposited the Aphids on it that very little harm should be done. 

 If it is absohitely necessary to follow with a second maize crop, the 

 infested land should be deeply ploughed and thoroughly harrowed 

 in the autumn ; this wall destroy many winter nests of the ants. 

 Besides maize, A. maidiradicis attacks broomcorn and sorghum and 

 many uncultivated plants. 



