72 Bulletin of the Brooklyn Entomological Society Vol. XV 



Laboulbenia formicarum belongs to the Laboulbeniacese, a 

 family usually included among the sac fungi or Ascomycetes and 

 exclusively found growing on living arthropods. Of the 600 or 

 more described species of these fungi, the great majority attack 

 beetles ; only the three following have been hitherto recorded 

 from ants. Rickia Wasmannii Cavara is the only ant-infesting 

 form known from Europe, where it grows on Myrmica Icevinodis 

 Nylander and on M. scahrinodis Nylander. Rickia formicicola 

 Spegazzini, recently described, was found on Prenolepis silvestrii 

 Emery, in La Plata, Argentina. The hosts and distribution of 

 Laboulbenia formicarum Thaxter have been mentioned above. 

 These ant-inhabiting Laboulbeniacese are small and inconspicuous 

 fungi, and when examined in situ on the host, appear like minute, 

 usually dark-colored or yellowish bristles or bushy hairs, project- 

 ing from its chitinous integument either singly or in pairs, more 

 commonly scattered, but often densely crowded over certain 

 areas on which they form a furry coating; when infestation is 

 excessive, the ants have been properly compared with hedgehogs, 

 fairly bristling with tufts of the fungus (Wheeler). The de- 

 tailed structure of these fungi can only be studied with a proper 

 magnification, for the ant-attacking species are among the smallest 

 members of the family, rarely exceeding one or two tenths of a 

 millimeter in total length. Perhaps the most remarkable pecu- 

 liarity of the Laboulbeniacese is their ability to thrive freely on 

 their hosts without interfering much with its activity, inflicting 

 little if any appreciable injury. In the case of the ant parasites, 

 the parasitism is purely external, the fungus deriving its nourish- 

 ment in all probability from the superficial layers of chitin or 

 from deeper lying nutritive elements absorbed, without penetra- 

 tion, through the sucker-like foot. 



Of the other fungous parasites of ants, certain Hypocreacese 

 (Ascomycetes) of the genus Cordyceps are the most noteworthy, 

 being of rather large size and of not un frequent occurrence. In 

 this case, the polycellular mycelium pervades the tissues of the 

 host, which is rapidly killed, and often produces asexual spores 

 or conidia borne on external hyphse variously agglutinated or 

 united (Isaria stage). The mycelium finally produces outside 

 the body of the insect a boll-shaped or club-like organ or fructi- 



