. Ants; their structure, development and behavior. side. Just as it is difficult to make anything more than a purely artificialdistinction between small and large crater nests, so it is by no meanseasy to distinguish certain large craters from mound, or hill nests. Thelatter are usually much larger than the craters, not because they repre-sent more extensive excavation in the underlying soil, but because theyrepresent a large amount of material collected by the workers from theterritory surrounding the nest. This accumulation is perforatedthroughout with ga1leries and chambers and consists of
. Ants; their structure, development and behavior. side. Just as it is difficult to make anything more than a purely artificialdistinction between small and large crater nests, so it is by no meanseasy to distinguish certain large craters from mound, or hill nests. Thelatter are usually much larger than the craters, not because they repre-sent more extensive excavation in the underlying soil, but because theyrepresent a large amount of material collected by the workers from theterritory surrounding the nest. This accumulation is perforatedthroughout with ga1leries and chambers and consists of earth, small 2O2 ANTS. pebbles and vegetable detritus such as straws, twigs, pine-needles,leaves, etc. The propnrtim> of these various constituents differ greatlyin the different spirit -. In our eastern Ionnica ( Fig. 109)which constructs conical mounds sometimes a metre in height and twoto three in diameter at the ba>e. earth greatly predominates, whereas inthe Furopean /•. nt/a (Fig. 110) and our western subsp. obscnripcs. FIG. iii. Mound of thatching ant (Formica obscuripes) of Colorado, made of coarse twigs and grasses. (Original.) i Fig. ill) the dome-shaped nest consists of a mass of sticks orpine-needles resting on a large crateriform earthen base. InPogonomyrmex molefaciens and occidentalis ( Fig. 108) the moundconsists very largely of pebbles. The number and position of thenest openings is also highly variable. In F. nifa the numerous open-ings are scattered over the whole surface of the mound, in they are mostly aggregated in a broad belt around thebase, in inolcfacicns there is a single opening at or near the summit,whereas in P. occidentalis the single entrance is situated at the base, andalmost invariably on the southern or eastern side (Fig. 108). There canbe little doubt that the mound nests of the species of Pogonomyrmexmentioned above have arisen from the large crater, which is the onlyform of nest in most species of the ge
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Keywords: ., bo, bookcentury1900, bookdecade1910, booksubjectants, bookyear1910
