574 State Board of Agriculture, &c. 



weeks tliey hatch into grubs of a dirty yellow, or whitish 

 color, (figure 3, a,) with dark heads and two dark dots 

 on the first ring back of the head. They have a 

 singular and filthy mode of concealing themselves. The 

 vent is placed on the top of the last ring and after 

 stuffing themselves with leaves the dung falls in abun- 

 dance upon the back of the larva and is gradually pushed 

 forward towards the head until a mass accumulates 

 ' sufficient to cover the whole back with a greenish pulp. 

 This serves to protect the soft and tender body of the larva 

 from the sun and especially from the observation of its 

 enemies. When the covering becomes dry the larva shakes 

 it off and a new one takes its place. In about two weeka 

 after the larvse come from the egg they leave the potato, 

 descend to the ground and form a cell of earth in which 

 they change to chrysalids, in which condition they remain 

 for about two weeks, and then they emerge as perfect 

 beetles and climb up the potato stalk and anew devour the 

 leaves and lay their eggs. Thus there are two broods of 

 this insect each year. The only remedies seem to be hand 

 picking, or Paris green, and there is no reason why the 

 latter remedy might not be as efficacious against this pest 

 as against the Colorado beetle. 



We now come to the chiefest agent among insects in the 

 destruction of the potato, the famous ten-lined potato 

 beetle {^Doryphora decemlineata, Say). 



