REPORT OF THE STATE ENTOMOLOGIST I914 45 



this midge would suggest a probability, at least, that ordinarily it 

 was not particularly destructive, and if this be the case, natural 

 enemies, especially parasites, are probably the controlling agency. 

 If such exist they should be obtained and colonized in this country 

 so as to provide for a more or less perfect natural control. 



Remedial measures. The investigations of Professor Chaine 

 lead him to advise the dusting of the under side of the leaves with 

 flowers of sulphur, making the application at about the time the mid- 

 ges commence to fly and, if necessary, repeating it once or twice in 

 order to secure complete protection. He advises a preliminary 

 wetting of the foliage and then the dusting from the under side. He 

 is of the opinion that even road dust is nearly as effective, and was 

 led to adopt this method after observing the comparative immunity 

 of box plants growing near dusty highways. More or less difficulty 

 would be experienced in keeping the leaves sufficiently dusted to pro- 

 duce the desired results, and in the case of an ornamental plant this 

 is to be avoided if possible. 



Two or three sprayings of a contact insecticide such as kerosene 

 emulsion or a whale oil soap solution applied when the midges, are 

 beginning to issue and distributed during the period of flight, ap- 

 peared to be very effective in controlling this midge, according to 

 statements from Mr Butterton of Newport, R. I., received through 

 the kindness of Prof. A. E. Stene of Kingston. 



A series of laboratory experiments were conducted by the Ento- 

 mologist last fall for the purpose of ascertaining the possibility of 

 destroying these miners while still within the leaves. Carbon bisul- 

 phid, ammonia gas, hydrocyanic acid gas and vapors from flake 

 napthalene were the materials employed. There was no difficulty 

 in killing the larvae with the first two named, and the maggots 

 showed the effects of treatment with the latter two. The great 

 difficulty with ammonia was that it seriously injured the foliage as 

 well as destroyed the maggots. These laboratory experiments in- 

 dicate a probability, at least, that fumigation with ordinary com- 

 mercial carbon bisulphid, using one teaspoonful for each five quarts 

 of space and continuing the action at least one hour and probably 

 two or three hours, would result in the death of most of the maggots 

 with little or no material injury to the box plants. It would be 

 necessary only to provide some suitable form of an air-tight, flexible 

 box or tent which could be put over section after section of the in- 

 fested hedge. The insecticide should be placed in shallow pans or 

 saucers. The larger the area of the liquid, the quicker evaporation 

 and more effective the treatment, other things being equal. We are 



