September 30, 1904.] 



SCIENCE. 



439 



will not confine itself to boll-weevils, even if 

 it succeeds in surviving the winters and floods 

 of Texas. If we except a few vegetarian 

 species like the curiously modified fungiis- 

 growing Attii, ants, like human beings, thrive 

 best on a varied diet. Cook says that ' The 

 discovery of the ant [the kelep] supplies a 

 practical reason for the existence of the 

 nectaries [of the cotton plant] hitherto quite 

 unsuspected, and it suggests the further pos- 

 sibility that the weevil and the ant have been 

 factors in the evohition of the cotton plant, 

 for the weevil is not known to feed on any 

 plant except cotton.' This statement is 

 clearly at variance with the current views of 

 many botanists and myrmecologists, who have 

 compared the much exaggerated and largely 

 fictitious accounts of the dependence of plants 

 on protecting ants with the actual conditions.* 

 Furthermore, even if we accept the views of 

 Schimper and some other botanists in regard 

 to the protection afforded plants by these in- 

 sects, we should still be unable to understand 

 why the boll-weevil was not long ago extermi- 

 nated by the kelep, inasmuch as the beetle is 

 clearly injurious to the cotton plant and hence 

 to the supposed best interest of the ant. 



The above considerations indicate that there 

 is little probability that the kelep can be suc- 

 cessfully established in Texas or adjoining 

 states, or, if established, that it will be an ap- 

 preciable factor in the extermination of the 

 boll-weevil. This becomes even clearer if we 

 glance for a moment at the more general sub- 

 ject of the introduction of ants into foreign 

 countries. At first bkish ants would seem to 

 be the easiest of all insects to introduce, since 

 the fertilized queen is long-lived and capable 

 as an individual of producing a whole colony 

 of all the three sexual forms so characteristic 

 of these and other social insects. Moreover, 

 the young brood is efficiently protected from 

 danger by the workers and not left to shift for 

 itself as in most insects. But when we come 

 to enumerate the species that have been able 

 to survive in foreign lands, we find it to be 



* See, e. g., the excellent article by Ernest 

 Rettig, ' Ameisenpflanzen — Pflanzenameisen : Ein 

 Beitrag ziir Kenntnis der von Ameisen bewolmten 

 Pflanzen und der Beziehungen zwisclien beiden,' 

 Jena, Giistav Fischer, 1904. 



very small, limited to a few genera and com- 

 prising several more or less dubious cases. In 

 my opinion the following are all the foreign 

 ants that can be supposed to have established 

 themselves in this country since it was opened 

 up to commerce: Tetramorium ccespitum, T. 

 guineense and T. simillimum; Monomorium 

 pharaonis, M. floricola; Pheidole megacephala, 

 Prenolepis longicornisj P. piibetis; Plagiolepis 

 longipeSj and some doubt attaches to all of 

 these forms except M. pharaonis, the tiny 

 yellow house-ant of Old World origin. It 

 is an open question whether T. cmspitum has 

 been introduced into the United States. It 

 seems to occur only along the Atlantic coast 

 from Connecticut to Maryland, but it is quite 

 possible that it may be indigenous. The re- 

 maining species in the above list are all tropi- 

 eopolitan and may all be indigenous to the 

 tropical and subtropical portions of our conti- 

 nent, for the conditions in these regions are 

 much more generally favorable to ant-life 

 than they are in temperate regions. All of 

 these species are occasionally met with in our 

 northern green-houses.* 



Considering the ease with which incipient 

 ant colonies and single fertilized queens are 

 carried from one country to another in wood, 

 hot-house plants, soil, minerals, etc., this list 

 is surprisingly meager, even if there were 

 sufficient evidence to prove that the species 

 enumerated are all hona fide importations. 

 Incidentally it should be noticed that none of 

 these are Ponerins, but all belong to the two 

 dominant subfamilies, the Myrmieinse and 

 Camponotinse.f 



One of the reasons for this small number of 

 imported Formicidse would seem to be the 

 extreme sensitiveness of these insects to 



* Further study of Formica cinerea and F. 

 rtifibarhis convinces me that they can not have 

 been imported from Europe, as I once supposed 

 possible. 



f Some idea of the number of species of ants 

 accidentally introduced with hot-house plants at 

 a single port (Hamburg), may be obtained from 

 two of Forel's recent papers : ' Fourmis Importges,' 

 Bull. Soe. Ent. Suisse., Vol. 10, 7, pp. 284-287, 

 1900, and ' Formiciden des Naturhistorischen Mu- 

 seums zu Hamburg, Mitth. a. d. Naturliist. Mus., 

 18, 1901. Anhang., pp. 78-82. ■ 



