THE PHYTOMYZA LEAF TUNNELLER. 73 



&c., as are affected, as the pest spreads rapidly when not 

 carefully watched, which, when the plants are growing 

 out-of-doors, is a most difficult task to perform. 



To those who have plants growing under glass my 

 advice is keep the tobacco smoke going as frequently as 

 possible, and if one or two plants show signs of having 

 been attacked by this little fly remove or destroy them 

 if not valuable, then dipping must be resorted to, as the 

 larva, being safely enclosed in the blister-like covering, 

 is beyond the reach of poison, or even the ordinary 

 preparations in use for leaf-feeding insects generally. 



