Stonefly larvae

All insecticides affected the mobility of . riparius larvae in a similar manner. A normal swimming motion was generally reduced to 1 cycle at the onset of toxic symptoms. The effect of the toxicant increased until the larva lost all ability to move. Death soon followed. Similar symptoms of insecticide poisoning have been reported for stonefly naiads (13, 14). Changes in larval color were unreliable for determining toxic affect. Toxic symptoms were observed in approximately 50-75% of the midge larvae immersed in 20 ug/L aldrin at the end of the 2 hr exposure but no effects were noted with aldrin plus PBO. All larvae immersed in dieldrin, or dieldrin with PBO were moribund. 

The remainder of this section discusses the two application problems recognizing stonefly larvae and classifying soil mesofauna. For each apphcation, we describe the motivation for choosing the taxonomic identification task and the methods for manipulating specimens and capturing images. 

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