220 JOURNAL OF ECONOMIC ENTOMOLOGY [Vol. 5 



exposed to attack and is knowai to be capable of serving as a host for 

 the scale should be fumigated, even though scale has very rarely been 

 found on it. The fact that it is known to be able to harbor the scale, 

 makes it a dangerous plant and justifies the demand that it be treated. 

 It seems to be the case that some plants are more susceptible to attack 

 in some localities than in others. But the fact that a plant is suscep- 

 tible in any locality places it under suspicion. 



In determining what plants should be fumigated and what ones may 

 safely be exempt, Doctor Britton's list serves as a safe guide. All 

 plants in the first and second lists, and a few included in his third list 

 which have been reported as infested since its publication should be 

 fumigated; those remaining in the third list may safely be exempt 

 except when they stand in very close proximity to infested stock. 

 Some of the shrubs of that list which should be excluded are as fol- 

 lows : Wistaria, and Cercis canadensis reported as infested by Prof. G. 

 M. Bentley; Staphylis sp., reported as badly infested in one instance 

 by Prof. A. E. Stene, and Rhamnus which has been found quite 

 badly infested in Illinois; and there are perhaps others. 



The evidence thus far as to the non-susceptibility of the remaining 

 plants of this list seems to be chiefly of a negative character. There 

 is need of experiments along this line to secure positive evidence. 

 It is probable that experiments will prove that the scale is not able 

 to come to maturity and produce a new generation on some of the plants 

 which have been reported as rarely or slightly infested. 



I feel sure that a full consideration of this subject at this time, or 

 some future time, will prove profitable even though we may not be 

 able to come to a mutual agreement as to a uniform method of pro- 

 cedure. 



ENFORCING FUMIGATION AND THE ATTITUDE OF NUR- 

 SERYMEN AND GROWERS TO THE TREATMENT 



By T. B. Symons, College Park, Md. 



The object of this paper is primarily to bring up a discussion of this 

 subject among members of this Association, looking towards uniform 

 requirements by the State Inspectors, and to point out how this work 

 is being conducted in Maryland. 



It is unnecessary to discuss before this Association the large amount 

 of work that has been done in the past to assure us that fumigation 

 with Hydrocyanic Acid Gas is the best, and at the same time a safe 

 treatment, when properly conducted, of nursery stock liable to be 

 infested with scale insects or other pests, that can be employed. 



