263 ^ JOURNAI. OF ECONOMIC ENTOMOLOGY [Vol. 1 



a temperature considerably above its "critical point," or absolute 

 minimum. 



Snowfall wiU exercise an important influence in limiting the effect 

 of minimum temperatures. Thus the present season the Rose Chafer 

 (Macrodactylus suhspinosus), whose larva winters in the soil, has been 

 exceptionally abundant, and the Striped Cucumber Beetle (Diahrotica 

 vitatta), which hibernates in the earth, has been as injurious as 

 usual, in spite of the low temperatures of last winter, both having 

 been protected by the deep snow blanket. Species hibernating above 

 ground will therefore be most susceptible to minimum temperatures. 

 Humidity will also materially affect the influence of minimum tem- 

 peratures. 



From the above discussion it seems that the following conclusions 

 may safely be drawn : — First, that the present Upper Austral Zone of 

 Doctor Merriam does not extend far enough to the northeast and 

 extends too far to the northwest. Second, that there is strong evi- 

 dence against the effective temperature of the growing season being 

 the only or controlling factor in detei'mining the northern limits of 

 life areas. Third, that minimum temperatures often limit northern 

 distribution. Indeed, is it not probable that the laws governing the 

 disti-ibution of life are a ccmiplex resulting fi-om many different 

 causes which are of variable im])ortance with each species? Though 

 hypotheses concerning the general principles involved are of the great- 

 est value in forming a basis for further investigation, yet the true 

 life zones can only be ascertained by a patient accumulation of data 

 concerning the actual distribution and spread of life as found, when 

 a comparison with the known physiographical and meteorological con- 

 ditions will make apparent the laws underlying the distribution of 

 life. 



TWO INTERESTING INQUILINES OCCURRING IN THE 

 NESTS OF THE ARGENTINE ANT 



WiLMo.N Newell. Buton Rouge. La. 



In the February is.sue of the Journal quite lengthy mention was 

 made of the habits of the Argentine ant, Iridomijrmex humilis Mayr, 

 M'hich has become a pest of serious nature in the southern parts of 

 Louisiana and jNIississippi. 



Although the writer has had this species under constant observation 

 for the past ten months, not a single parasitic or predaceous enemy of 

 it has been discovered. The insects which dwell with this ant, in its 

 colonies, are verv scarce and none of the true insects are as yet posi- 



