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ENTOMOLOGICAL NEWS. 



[April, '08 



effect, the diagram should be viewed at a distance of ten feet, 

 when the difference in degree will be seen without detail. 



United States. Bermuda. 



The average road in the United States is about the color of 

 a plowed field, and hence of little effect in modifying the gen- 

 eral shade. In Bermuda the roads are closer than in Penn- 

 sylvania, and hence effective in lightening the general aspect 

 of the country and added to this, the roofs increase the ef- 

 fect, and although an insect in its flight might many times 

 fly over or alight on a dark background, among the thousands 

 of objects visible, of two insects of one species, the slightly 

 darker one will be the first discovered on a light background; 

 the lighter ones will live the longer and naturally have more 

 descendants. 



It seems unnecessary since acquaintance with Darwin's the- 

 ory is so wide-spread, to say that although all animals resem- 

 ble their parents, they all vary in minor particulars, and any 

 difference in color or otherwise may serve to protect one and 

 enable it to live long enough to produce its kind with a like 

 resemblance and a little immunity. Nature seizes upon that 

 which is good. 



It may be asked why these insects are not still lighter, but 

 here the law of equilibrium intervenes and prevents a further 

 advance. There is danger when it becomes too light of be- 

 coming too conspicuous. Taking an extreme case, a white 

 insect would be at once a prey of its enemies when on or over 

 the darker vegetation. They are held back far enough from 

 white to be fairly safe on a dark background. 



