36 



Journal of the Department of Agriculture. 



be no nearby sources from which a heavy reintestatiou may come. 

 The question of the weeds, on which the insect lives, may, therefore, 

 be of importance. It is necessary to go over the plants frequently. 

 I was told that at the Experiment Station the examination was made 

 every three days. Apparently only the slugs and beetles were 

 destroyed. As the eggs take from four to seven days to hatch, and 

 the larvae from two to four days before tliey moult the first time, 

 and become seriously destructive, it will be seen that if the eggs 

 could be destroyed too, an examination once a week or once in ten 

 days should be sufficient. 



It seems worth while to try and kill as many of the beetles as 

 possible when searching through a field, though it is not yet known 

 what proportion of those present can thus be destroyed. In sunny 

 weather some are likely to take flight ; but it is said that if the beetle 

 is shaded with the hand it can be easilv secured. 



Fig. 2.— The Tobacco Slug. 

 Slugs on leaf of datura. 



Spraying. — As the insect is a leaf-feeder it may be killed by 

 applying a stomach poison, like arsenate of lead, to its food-plant, 

 and this method of controlling it will probably become more and more 

 popular. Arsenate of lead is recommended, because it is safe for 

 the plant, sticks well, and its readily piocurable. It is also now 

 manufactured in the country. It is obtainable in paste form and as 

 a dry powder, and is applied as a spray, used at the rate of 2 lb. 

 of paste or 1 lb. of dry powder in 50 gallons of water. The powder 

 is double the strength of the paste, and is generally preferable, except 

 when the paste is relatively cheaper. 



Some people have tried arsenite solution from the cattle-dipping 

 tank. Usually one trial was enough to prevent another, but, as it 

 has been stated that good results have been obtained with weak dilu- 

 tions, it may be that others may still be led to experiment with it. 

 It is, therefore, necessary to utter a warning against the iise of cattle 

 dip. A poison like arsenite of soda should stop in the dipping tank 



