4 SECOND REPORT ON ECONOMIC BIOLOGY. 



On large areas of land the only treatment of practical value is 

 the application of ground unslaked lime. For smaller areas the reader 

 is referred to the methods set forth in previous Reports. 



LEAF-HOPPERS. 



Typhlocybidae. 



Of the many neglected families of Hemipterous insects, the Leaf- 

 hoppers or Typhlocybidae are rapidly assuming a very prominent 

 position. They have been extraordinarily plentiful during the past 

 year, and have occasioned considerable damage to fruit, forest, and 

 ornamental trees, and particularly to garden produce, viz., beans, 

 peas, potatoes, etc. 



The two commonest species that have come under my notice 

 have been Chlorita flavescens, Fabr., and C. viridula, Fall. In one 

 case the latter species swarmed on French beans to such an extent 

 that on plants about four feet high it was difficult to find a sound 

 and perfect leaf, the majority being riddled with irregular slit-like 

 holes. Roses suffered in the same manner. 



The eggs are laid early in June on the underside of the leaves, 

 and the nymphs hatch out in from ten to fourteen days. After a 

 series of moults, extending over five or six weeks, the adult stage is 

 reached. A second brood appears early in August, and a third 

 appeared early in October. 



The nymphs, when first hatched, are almost white and very 

 active, later becoming a pale yellowish green. 



When young these insects are easily destroyed by spraying with 

 a paraffin emulsion, repeating the operation in a fortnight's time. 



The adults are more difficult to destroy. Upon spraying the 

 trees, etc., they make for a resting place on the ground, or fences if 

 near ; these latter should receive a good drenching with a strong 

 paraffin emulsion. 



THE CABBAGE APHIS. 



Aphis brassicae, Linn. 



Undoubtedly the greatest and most objectional pest attacking the 

 cabbage plant is this aphis. Often the actual amount of damage done 

 is small, but the plants become unmarketable owing to the slimy mass 

 of insects and their excreta. 



