FOREST COMMUNITIES 431 



whence they attach themselves to warm-blooded animals. 34 Of forest 

 insects the bugs (Heteroptera) are abundant; among the Orthoptera, 

 the blattids, mantids, phasmids, and locustids are well represented, 

 while the crickets and acridid grasshoppers that dominate the steppes 

 are relatively less important. In the interior of the forest, mosquitoes, 

 mites, and wood ticks attract attention by the annoyance they give 

 the collector. The ticks can burrow through the scaly legs or even the 

 carapace of a turtle and obtain blood. Of the bees, the earth-dwelling 

 bumblebees are entirely absent and are replaced by forms which make 

 their nests in wood or hang them from the branches. 



Termites, which furnish prominent representatives for the savanna 

 country, are also abundant in the tropical rain-forest even though 

 they seldom appear in the open. Their nests may be found in all strata 

 of the forest. These nests, made by cementing together soil or woody 

 particles, are connected to the ground by covered passages through 

 which the termites travel. In particularly rainy regions the nests are 

 equipped with gutter-like ridges which carry off excess water. The 

 termites are especially important in the forest economy because their 

 wood-eating habit greatly hastens the decay of woody materials. They 

 share, with the similarly social ants, the insect dominance of these 

 forests. 



Ants are to be found everywhere in the tropical forests. Many 

 species are entirely arboreal; the American Azteca, with more than 

 70 species, is so limited. These are to be contrasted with the leaf- 

 cutting but subterranean nesting Atta and with the driver or army ants 

 which roam through the forest in hordes, putting to flight all animals 

 able to escape. 35 As with the termites, the ants exhibit a great variety 

 of nests. 36 The ground nesting habit is less common, since, as with 

 other forms, there is a general moving upward into the shrub or 

 arboreal strata. Cavities in trees and branches are much occupied; 

 paper carton nests hang like stalactites from branches. Oecophylla 

 in the Indo-Malayan forests and Camponotus in Brazil use their 

 spinning larvae to fasten living leaves together into a nest. 37 The 

 Eciton ants of the American forest make their nest from their own 

 living bodies, which, when the time comes, disentangle and move off 

 with the horde through the forest. 38 Certain arboreal ants have es- 

 tablished epiphytic plants on their tree-top nests, especially brome- 

 liads, gesneriads, and rroids, thus making the so-called flower gardens 

 of the ants. Many ants live in special cavities, internodes, hollow 

 thorns, etc., of specially adapted ant plants which may provide food 

 for them in addition to concealment. This has been interpreted as a 

 return developed by the plant for the protection supplied by the ants. 39 



