The Tracheal System of the Larva of Lissorhoptrus Simplex*

The immature stages of the rice water weevil, Lissorhoptrus simplex (Say)[†][1], are passed entirely below the water, either in or among the roots of rice and other aquatic grasses. The eggs are deposited in the roots, and the female beetles will not deposit eggs unless these roots are submerged. The small larvae feed first within the roots in which they hatch, and as they grow larger they live in the mud around the roots upon which they feed. Pupation takes place in a water-tight cocoon attached to a rootlet. The entire time required for passing the immature stages in the insectary, from deposition of the egg to transformation to the adult stage, may be as brief as 32 days and as long as 77 days. The remedial measure recommended is temporary drainage of the rice fields, allowing them to dry until the ground cracks. This is very effective in destroying the larvae. [1]: #fn-2