320 Ohservaliom on Insects affeclimj the Turniii Crops. 



sewed or fastened round tlie iron ring ; or if a sheath of leather 

 be first fixed round the ring, the bag may be attached to it, which 

 wall make it last longer, and it can be more readily replaced when 

 it is w^orn out by sweeping herbage or other rough work. With 

 such a net any insects may be readily caught with a little practice. 

 The net described is adapted to brush bushes and sweep along the 

 ground^ &c. ; but if one be required for catching butterflies by 

 day, or moths in the evening, the ring must be lighter, the stick 

 may be made of a cane or bamboo, and the bag should be of silk- 

 gauze or bobbinet. 



Sum7nary of the foregoing Report. 



There are three species of White Butterflies which injure the 

 Turnip and Cabbage crops. 



The first is called the " White Cahhafje-butterflu '' which de- 

 posits its eggs in clusters on the under side of Cabbage, Turnip, 

 Mustard, Rape, Radish, Horseradish, and Watercress leaves. 



When first hatched the ccLterpillars live in society ; but when a 

 week old they disperse. 



They remain through the icinter in the Ch7"ysaUs state, sus- 

 pended in secure retreats in walls, paling, &c. 



The ccderpiUars greatly injured some Swedish turnij).s last 

 September. 



They do still greater mischief by eating off all the j^ods, in 

 crops of Turnij)S and Mustard left for seed. 



The full-grown caterpillars died suddenly of some disease after 

 a wet night, during very hot weather. 



Cabbages in cottage -gardens might be readily freed from this 

 pest by hand-picking. 



A Parasitic fly, called Microgaster glomeratus, lives in and 

 destroys great numbers of the caterpillars. 



The little yellow silken cases found round the dead caterpillars 

 should never be destroyed, as they contain these useful parasites, 

 whose operations are certain and invaluable. 



Igjuyrant persons destroy them, believing them to be the eggs 

 of the caterpillars; but caterpillars never lay eggs. 



The Microgaster has also a smaller parasite which lives upon 

 it, called Diplolepis Microgastri. 



A large Ichneumon, called Pinipla instigator, also lives in the 

 caterpillars of the White Cabbage- butterfly. 



Pteromcdus Brassicce and P. Poniicc, two other minute flies, 

 lay their eggs upon the Chrysalis, and materially assist in keep- 

 ing these butterflies in check. 



The second species, " The small White^ or *' Turnip bidterflyr 

 lays her eggs not in clusters, but singly, on the under side of the 

 leaves of Cabbages, Turnips, Mignonette, Nasturtiums, tScc. 



