Geographical Distribution of Insects. 103 



Temperature at once influences habitats and stations, but 

 its effect on the former is much greater than on the latter, 

 for it varies more from one country to another, than in the dif- 

 ferent localities of the same country. Yet it is of importance 

 for the entomologist to know in what the various stations dif- 

 fer in this respect, in order that he may regulate his research- 

 es accordingly. Thus, in om* temperate climates, certain 

 carabidae, such as the cychri, frequent, in preference, places 

 exposed to the north, while the opposite of this takes place 

 with the ateuchi. 



Influence of Light. — Light has little influence except on the 

 coloration of animals, and it would have been unnecessary to 

 mention it here, had it not been for the purpose of refuting 

 an often repeated assertion, that insects are more brilliant in 

 colour the nearer their habitat approaches the equator. This 

 is true in this sense, that more brilliant species are found in 

 intertropical countries than elsewhere, and that individuals 

 of the same species are more brightly coloured the more 

 southern the coimtry they inhabit. But there is another law 

 which seems to have regulated the coloration of these ani- 

 mals, viz. that species are more brilliant in those regions which 

 are to be regarded strictly as their native country, than in 

 any other situation. We may find a proof of this in the carabi, 

 which predominate in the northern temperate zone ; the Si- 

 berian species, which are very numerous, being fully equal 

 in colom* to those of Southern Europe and the coasts of 

 Barbary. 



According to Avhat we observe in regard to plants, we 

 might expect that the kinds which live on mountains 

 would be more deeply tinted than such of their species as in- 

 habit plains, but the contrary is most frequently the case. In 

 the Alps of Dauphine, for example, there is a variety of Cara- 

 bus aiiratus, which is quite dull compared mth the t}q)e of 

 the species found in other parts of France. 



Light has an influence on stations merely. Many species 

 delight in almost complete obscurity ; others prefer the deep 

 twilight of forests. In general, it is those only possessing 

 powers of easy and rapid flight, which expose themselves for 

 a long time to the ardent heat of the sun ; these are also ob- 



