204 OH T O EXPERIMENT STATION: BULLETIN 194 



EXPLANATION OF PLATE H. 



Fig-. 1. The rose scale, natural size. 



Fig. 2. The maple cottony scale, natural size. 



Fie. 3. Lombardy poplar on the campus of Buchtel College, Akron, 

 Ohio. This tree is badly infested 'with oyster shell bark louse. 

 The horse chestnut is badly infested at the base; the next in 

 order a little less so; the next one a little less, etc., down the 

 l : ne. It is a most striking- illustration of how scale insects 

 spread from a badly infested center. 



