Larvae and their Work 



floating leaves of water-lily and deposits her eggs either 

 in a single or double row around the hole, and on the 

 under side of the leaf. The larvae feed on the water-lily 

 roots, spending all their time below water ; they have no 

 gills nor other organs to fit them for such a life, for which 

 they appear ill adapted. The manner in which these 

 larvae obtain air is ingenious in the extreme. 



Now water plants differ from land plants in that they 

 have large air-spaces enclosed in their tissues, and this 

 enclosed air is stolen by our little insect. On the hinder 

 end of his back there are two curved spines which are 

 connected with breathing tubes. Naturalists noticed that 

 the roots frequented by these larvae bore sundry slits and 

 scars, always at about the same distance from one another, 

 and the distance was the length of a larva. Further in- 

 vestigation showed that the cute little creature inserted 

 its spines into the roots of the water-lily and pushed 

 them home till they reached the air-spaces within ; it 

 literally tapped the roots of air. The cocoon of this 

 insect is no less ingenious. It is a close-woven silken 

 structure closely applied to the root, but on the side which 

 is in contact with the plant there is no silken wall. The 

 outside of the root forms the wall and is punctured with 

 many holes through which air passes to the chrysalis. 



Another point worthy of mention is that, as a rule, 

 wounds on these roots quickly heal, a happening that 

 would be fatal to the chrysalis, seeing that it is quite 

 unable to keep the air-holes open. By one of those 

 provisions of which Nature shows so many examples, the 

 wounds, in this case, do not heal till the cocoon is either 

 removed or destroyed, till water is allowed to enter, in 

 other words. 



There are other case-makers which we must consider, 

 land case-makers though. The bag worms, of which some of 

 the finest examples are found in Australia, build larva cases 

 nearly as diverse in structure as are the cases of the various 

 caddis-flies. Most of these cases are built of small sticks, 



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