96 



and the cyanide was weighed out and placed b}^ the jars. Every- 

 thing being in readiness, the attendants put in the cyanide by begin- 

 ning on the upper floors and passing rapidly to the lower floors. 

 The doors were then closed, locked, and kept so for two days. Brick 

 Avails being porous, and the windows not as tight as desired, much of 

 the gas escaped. Persons walking within 100 feet of the building, 

 on all sides except that from which the wind w^as blowing, could 

 detect the odor of the gas the entire time. This made it desirable to 

 leave the building closed for a period longer than usual. Whon the 

 building was opened two days later most of the gas had escaped. 



The insects were very abundant and in all stages of growth, and 

 in many cases the eggs almost coated the slats on the beds. Many of 

 the eggs had hatched several Aveeks earlier, however, and it was nec- 

 essary to pick them over carefully to find good ones for observation. 

 This w^as done, and 10 apparently sound eggs were taken to the 

 laboratory and placed in " stender " dishes for examination before the 

 charges Avere placed. The day after the building was opened 101 

 eggs that had not hatched were collected, and these also Avere placed 

 in " stender " dishes for examination. All of the eggs in the first 

 lot (i. e., those taken before fumigating the building) hatched Avithin 

 ten days. The eggs collected after the building Avas fumigated were 

 examined every fcAv days for two Aveeks. but not a single one liatchecl, 

 and they shriveled up and lost their plump appearance after a fcAv 

 Aveeks. 



An examination of the insects the day after the building Avas 

 opened proved that all Avere dead and no eggs appeared to hatch 

 afterAvard, although examinations Avere made frequently for a i^eriod 

 of several Aveeks. Though this work Avas done in June, scarcely an 

 insect could be found in the building as late as December 22. This 

 appears to be conclusiA^e evidence that fumigation Avith hydrocyanic- 

 acid gas Avill destroy some classes of insect eggs. It is likely to be 

 most effectiA'e on those Avith a large micropjde, like that of the eggs 

 in question, and might not be eft'ectiA'e on those Avith heaA'y shells 

 suited to stand weather conditions in the field. We are now arrang- 

 ing to stud}^ its efl'ect on the eggs of the scurfy scale {Chionaspis 

 furfura Fitch). 



Rooms used for storing food products haA^e been treated by fumi- 

 gating Avitli hydrocyanic-acid gas under our directions also. These 

 rooms had become seriously infested Avith the croton bug {BlatteUa 

 germanira Linn.). Before fumigating these rooms all food prod- 

 ucts that had been opened, such as butter, lard, etc., in fact, all 

 materials Avith a moist exterior, were remoA'ed from the building. 

 Such materials as boxed oatmeal, coffee, flour, sugar, canned goods, 

 sealed packages of preserves, etc., were left inside, 



