COCKROACHES AND HOUSE ANTS. 



97 



doing' this except to locate the nest by following the workers back to 

 their i)oint of entrance. If in a Avail the inmates may sometimes be 

 reached by injecting bisulphide of carbon or a little kerosene. It' under 

 flooring it may sometimes be possible to get at them by taking up a 

 section. Unless the colony can be reached and destroyed all other 

 measures will be of only temporary avail. 



The little black ant ( M onomorium minutum Mayr) (fig. 44) is not strictly 

 a house species, although frequently occurring indoors, and becoming at 

 times quite as troublesome as the red ant. Its colonies usually occur 

 under stones in yards, but are frequently found in the fields, and will 

 be recognized from the little pyramids of fine grains of soil which sur- 



FlG. 44.— The little black ant (Monomorium minutum): a, female; b, same with wings j c, male; d, 

 workers; e, pupa ; /, larva ; <j, egg of worker — all enlarged (original). 



round the entrances to the excavations. If these colonies be opened 

 they will be found to contain workers and usually one or more very 

 much larger gravid females. This species, when occurring in houses, 

 can often be traced to its outdoor colony, and the destruction of this 

 will prevent further trouble. 



The pavement ant of our Eastern cities ( Tetramoriwn oasspitum Linn.) 

 (fig. 45) is in Europe the common meadow ant. and is two or three times 

 larger than either of the other species referred to. It was early intro- 

 duced into this country, and, while not yet reported from the N\ est. is 

 very common in Eastern towns, and particularly here in Washington. 

 It has readily accommodated itself to the conditions of urban exist erne, 

 2805— No. 4 7 



