Vol. LI. LONDON. NOVEMBER, 1919. No. 11 



POPULAR AND PRACTICAL ENTOMOLOGY. 



Further Remarks on Collembola. 



by charles macnamara, arnprior, ontario. 



A ven.' remarkable feature of the Collembola is their amazingly wide dis 

 tribution. They are found all over the world, and as Dr. Folsom remarks' 

 "may be expected to occur wherever there is a soil that supports vegetation." 

 The one condition fatal to them is dryness. Some of the scaled kinds are said 

 to live in comparatively arid situations, but the vast majority can exist only in 

 a decidedly moist atmosphere. Given a modicum of humidity, however, they 

 can make themselves at home anywhere. You can collect them on cloud- 

 capped mountains, under the dense shade of forests, over grassy plains, along 

 the sea shore, or in your own wood-shed at home. They are perhaps most 

 abundant among the moss, dead leaves, and rotten logs of woodlands, but they 

 are common also in fields, gardens, and green-houses. They shelter under the 

 bark cf trees, (I have found them living at the top of a 75- ft. maple) — they are 

 plentiful in long grass and damp soil, and certain over- ripe toadstools often 

 swarm with them. They are counted among the unbidden guests in ants' 

 nests, and one species is known in the United States as a household pest, though 

 admittedly a very minor one. Many frequent caves, — some species occur 

 nowhere else — others find their way deep down into mines, and one ghastly 

 white Isotoma (/. sepulcraUs Pols.) makes its hideous habitation with moulder- 

 ing human bodies in the grave. Some occur along the sea shore, and may be 

 submerged by the tide for hours every day without hurt. Others live on the 

 banks of fresh-water streams, and many venture out on to the surface of ponds. 

 A curious accident sometimes happens to these aquatic kinds. The "surface 

 skin" of the water is for them a firm floor which they cannot break through, 

 but occasionally an adventurer among them, by crawling down the steiti of a 

 water plant, penetrates beneath the surface. If he returns by the same road, 

 good and well; but if he lets go of the plant, he at once floats up against the 

 under side of the water film, and being as unable to break through from be- 

 neath as he was from above, he perishes miserably. 



Quite as remarkable as this "sub- ubiquity" of the order is the exceedingly 

 wide range of certain genera and species. The name of the springtails common 

 to the whole Northern Hemisphere is legion; indeed no other order of animals 

 is known to show such a large proportion of Holarctic species. Isotoma palustris 

 Mull., to mention only one, abundant on water in this country, is domiciled 

 also in California, Great Britain and Siberia. Other species range even farther. 

 Sminthurus hortensis Fitch, which you are sure to find in your garden in May* 

 and June if you look for it, is a resident also of Scotland, Bohemia, Japan and 

 Tierra del Fuego. Achorutes armatiis Nic, plentiful everywhere in our woods, 

 is recorded from Greenland, Spitzbergen, Great Britain, Switzerland, North 



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