INSECT PESTS AND DISEASES. 105 



the grub turns to a chrysalis, and in a very short time 

 emerges as a perfectly developed fly. The grubs of the 

 leaf, moreover, are to be found on the plants in the autumn 

 when the latter are housed. A cool temperature retards 



Leaf Mining Maggot. 



their development, but in a warm atmosphere they in- 

 crease and multiply at an amazing rate. Umless prompt 

 measures are taken to destroy the flies, and so prevent 

 them laying their eggs, an incalculable amount of harm 

 will result. The best remedy is to smoke the plants and 

 houses with "Auto-shreds." My plan is to carry out the 



