86 ASSOCIATION OF ECONOMIC ENTOMOLOGISTS. 



on the leaves of ash trees, and is at present in our breeding cages, 

 awaiting its transformations, that we may identify it. 



Four houses in the Twin Cities — Minneapolis and St. Paul — to our 

 certain knowledge, and there were doubtless others, have been overrun 

 with the so-called " book-lice " (Troctes divinatoria Mull.). In these 

 particular cases these tiny pests swarmed in bureau drawer- and 

 closets, over clothing on walls, and the backs of pictures, and. in fact, 

 in every place where their presence was likely to disgust a sensitive 

 housekeeper. We made an effort to free two houses of this unwelcome 

 guest, and partial success was attained by the use of hydrocyanic-acid 

 gas. the families vacating the premises in question for about thirty 

 hours. TTe were unable to locate the starting point or breeding place 

 of the insect in these two cases. It is significant that all of the resi- 

 dences known to be infested are new houses, built within a year, the 

 present occupants being the first to use them. TTe are constrained to 

 believe, from our observations, that these insects came from the space 

 between the wails or under the floors, or both. A curious fact was 

 noted in connection with this piece of work. I have always been led 

 to suppose that this hydrocyanic-acid gas will not affect metal, if it 

 is perfectly dry. ITe had every reason to believe that the silver and 

 other metallic objects in these houses were free from moisture, and yet 

 when we finished we found that the silver which was outside of the 

 drawers in the dining room was tarnished, as was all the nickel on 

 the range in the kitchen, and the exposed plumbing in the bath- 

 room, which was plated with nickel. The silver was restored to its 

 pristine brightness by a jeweler, but the family has been unable to get 

 rid of the dull-brown discoloration on the nickel work. This could 

 be easily prevented by the use of vaseline, if one had reason to suspect 

 a recurrence of the trouble. Before this fumigation we suspected 

 that these insects might have their origin in the filling between the 

 floors. This filling is made of a dried seaweed. But if this was so. 

 we failed to discover it upon taking up some of the flooring and 

 examining the filling in question. 



Another family, which for two years or more has been troubled by 

 that very common household pest, the little red ant {Monomorium 

 pharaonis L.), has appealed to the entomologist for relief. TTe find 

 that these insects come from the walls of the furnace room in the 

 cellar, supposedly having their uests between the double wall- in this 

 locality, or in the soil outside far below the frost line. At date of 

 leaving St. Anthony Park we are still fighting this ant. having used 

 many pounds of bisulphid. with an apparent lessening of their num- 

 bers, yet we still find some coming through cracks and crevices of the 

 plastering. 



An interesting piece of work of the year, and perhaps the largest 

 operation of the kind ever conducted with hydrocyanic-acid gas, has 



