160 HALF HOURS WITH INSECTS. [Packard. 



The only possible way to study the aquatic insects is to 

 keep them in glass jars and bowls, where their habits can be 

 carefully studied. An aquarium may thus be improvised 

 which will last for several weeks without care, though it is 

 better to add a few water plants, such as the water cress, the 

 Valisneria, Callitriche, Duckweed and other plants, to keep 

 the water ox3'genated. By stocking the aquarium with the 

 larvoe and pupse of certain neuropterous insects at the time 

 when the Avinged forms are most abundant, the immature 

 forms can easily be kept long enough for us to determine the 

 winged species into which they pass. In the autumn, as 

 cold weather and short days keep us indoors, much profit 

 and solid amusement may be gained by these studies of 

 pond life within the house. Even in winter after the snow 

 is on the ground, one can break through the ice of roadside 

 ponds and with a small net capture nearly all the insects we 

 have spoken of in this number, and keep watch upon their 

 habits, and study their anatomy, with the aid of the needle 

 and lens. He can also turn to the lower forms, such as the 

 water fleas, rotifers, infusoria and rhizopods, with which the 

 waters teem winter and summer, and find, with a few dips 

 of tlie net, material for weeks of observation and study. 



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