1907.] 



Wheeler, Fungus-growing Ants of North America. 



697 



Fig. 2. Eggs and fungus gar- 

 den in cell of queen Atta sexdens, 

 forty-eight hours after the nuptial 

 flight. (After J. Ruber.) 



consists of fungus hyphse imbedded in the substances collected from the ant's 

 body by means of the strigils on her fore feet and thence deposited in her 

 mouth. By the third day 6 to 10 eggs are laid (Fig. 2). At this time also 

 the pellet begins to send out hyphffi in all directions. The female separates 

 the pellet into two masses on this or the following day (Fig. 3). For the 

 next 10 to 12 days she lays about 10 eggs daily, while the fungus flocculi 

 grow larger and more numerous. At first the eggs and flocculi are kept 

 separate, but they are soon brought together 

 and at least a part of the eggs are placed on 

 or among the flocculi. Eight or ten days later 

 the flocculi have become so numerous that they 

 form when brought together a round or ellip- 

 tical disc about 1 cm. in diameter. This disc 

 is converted into a dish-like mass with central 

 depression in which the eggs and larvae are 

 thenceforth kept. The first larvae appear 

 about 14 to 16 days after the Atta female has 



completed her burrow, and the first pupae appear about a month after the 

 inception of the colony. By this time the fungus garden has a diameter of 

 about 2 cm. There are no "kohlrabi" corpuscles in the earlier stages, and 

 when first seen they are at the periphery of the disc. A week later the pupae 

 begin to turn brown and In a few days the first workers hatch. Hence the 

 time required for the establishment of a colony under the most favorable 

 conditions is about 40 days. After this rapid survey of the matter, Huber 



asks the important cjuestion: How does the 

 Atta female manage to keep the fungus alive? 

 Obviously the small amount of substance in 

 the original pellet must soon be exhausted and 

 the growing hyphae must be supplied with 

 nutriment from some other source. His inter- 

 esting answer to this question may be given in 

 his own words: "After carefully watching the 

 ant for hours she will be seen suddenly to tear 

 a little piece of the fungus from the garden 

 with her mandibles and hold it against the tip of her gaster, which is 

 bent foi-^ard for this purpose (Fig. 4). At the same time she emits from 

 her vent a clear yellowish or brownish droplet which is at once absorbed by 

 the tuft of hyphae. Hereupon the tuft is again inserted, amid much feeling 

 about with the antennae, in the garden, but usually not in the same spot 

 from which it was taken, and is then patted in place by means of the fore 

 feet (Fig. 5). The fungus then sucks up the drop more or less quickly. 



Fig. 3. Eggs and fungus gar- 

 den in cell of queen Atta sexdens 

 seventy-two hours after the nup- 

 tial flight. (After J. Huber.) 



