1911] Mann — Calif ornian Ant Guests 29 



moved with the Formicas, or had found and entered the nest 

 later. Tapinoma does not harbor Hetwrius as a rule. The 

 very long hairs covering the dorsal surface of Hetwrius cali- 

 fornicus give the little beetle a distinctive appearance and it 

 is undoubtedly a true symphile. When disturbed, it either 

 feigns death or walks awkwardly awaj'. 



Formica cinerea var. neocinerea Wheeler. Not common. 

 I have myself found no myrmecophilous insects with this ant, 

 but have before me Hetcerius tristriatus Horn, taken at Lake 

 Merced, Cal., March 6, 1910, by Mr. F. X. Williams. 



Formica rufa var. near coloradensis. Several mounds 

 along Corte Madera Creek were examined, but nothing taken 

 except Myrmecophila formicarum, which was abundant. On 

 March 13, in a colony under a board were two specimens of 

 Batrisus zephyrinus Casey. They were walking about among 

 the ants, which paid no attention to them. 



Formica fusca var. argentata Wheeler. Common. Gen- 

 erally in damp locations in the hills. I have taken four speci- 

 mens of Hetcerius tristriatus, one each from four nests of this 

 ant on April 17, 1910. 



Prenolepis imparls Say. Common in damp places. This 

 is our local honey ant, but the workers away from the nest are 

 as often seen on carrion or dung as on anything from which they 

 might obtain honey. It harbors Myrmecophila formicarum, and 

 often the thief-ant, Solenopsis molesta Say. 



Tapinoma sessile Say. Abundant everywhere. Myrme- 

 cophila formicarum occurs in most of the nests, and colonies of 

 Solenopsis molesta are common. The nest of one little colony 

 of Tapinoma contained a colony of Sole?topsis approximately 

 five times as numerous in individuals as the host colony. 



On December 22, in a nest containing colonies of both Tapi- 

 noma and Solenopsis was a little wingless Proctotrypid, Iso- 

 hrachium myrmecophilum Ashmead. A second specimen was 

 taken from another nest on February 13. Ashmead^ states that 

 this genus is parasitic upon the ants or upon myrmecophilous 

 Coleoptera. The latter being so rare in the nests of Tapinoma 

 it is probable that Isobrachium is a parasite of the ant itself. 



iBull. 45, U. S. Nat. Mus. 



