in two generations per year, but these are not geneti- 

 cally distinguishable. 



There are 7 larval or instar stages. At hatching, 

 the larva has only 7 post-cephalic somites and 3 pairs 

 of legs. At each molt, more somites and legs are 

 added until in the adult there are 20 post-cephalic 

 somites and 30-31 pairs of legs. The first and second 

 instars are whitish in color, but later instars develop 

 a reddish-brown pigment. The April generation 

 reaches the morphological adult stage in the autumn 

 but sexual maturity not until the next spring. The 

 July generation overwinters in the 5th to 7th instars, 

 reaches the adult stage the following spring and 

 sexual maturity in June or July. Molting takes place 

 in small chambers similar to those in which the eggs 

 are laid. 



The egg chamber is unique. It is made of faecal 

 pellets containing ingested soil and organic material. 

 These pellets are placed in a ring of diameter about 

 6 mm. More and more pellets are piled on until the 

 ring reaches a height of about 3 mm. Some 200 to 

 400 eggs are then deposited inside the ring after, 

 which the ring is closed at the top to form a capsule. 

 The whole process requires 6 to 12 hours. After 

 breeding is completed, the adults die. 



SUMMARY 



Daily fluctuations of temperature, precipi- 

 tation reaching the ground, light intensity, and wind 

 velocity are greater in grassland than in forests, but 

 relative humidity is usually less. A gradient in habi- 

 tat conditions extends from above the vegetation to 

 the ground in both grassland and forest. Segregation 

 of animal species into subterranean, ground, herb, 

 shrub, and tree strata is partly explained by differ- 



ences in response to this gradient. North-facing 

 slopes are generally cooler, moister, and with lower 

 light intensities than South-facing slopes. 



The species composition of animals differs between 

 grassland, forest-edge, and forest. Within each com- 

 munity there is a vertical division into a subterranean- 

 ground society and an herb or herb-shrub-tree so- 

 ciety. Animal density and biomass are generally 

 greater in the former. Food, shelter, and microcli- 

 mate are the chief limiting factors. Outside of the 

 tropics, there is considerable seasonal variation in the 

 abundance of animals. 



Many niches are similar in forests of dififerent 

 types ; say, coniferous and deciduous. The species 

 occupying these niches are often different, however, 

 although they may have similar mores. 



Grasses tolerate considerable grazing, and grass- 

 land productivity may provide a high carrying ca- 

 pacity for large grazing animals. Overgrazing by 

 large populations of insects, rodents, or domestic 

 stock, however, may bring deterioration of the range. 

 Economic utilization of grassland requires proper bal- 

 ancing of grazing pressure against vegetative pro- 

 ductivity throughout the year. 



Forests are of great interest to man for timber, 

 protection of soil against erosion, and recreation. 

 Game species are usually more varied and abundant 

 in the forest-edge than in the forest-interior. Game 

 management is concerned with controlling the vege- 

 tation and habitat to produce the highest yield of the 

 desired species and to regulate the number taken. It 

 is necessary to know the intimate life-histories of 

 the species concerned before this can be accomplished 

 intelligently. Finally, it is of utmost importance to 

 ecological study that adequate samples of primitive 

 areas be preserved in an undisturbed condition. 



44 Ecological processes and dynamics 



