OF WASHINGTON, VOLUME XI, 1909. 75 



The making of the cocoon involves, according to Doctor 

 I loving, three distinct processes. \Yhcn ready to pupate the 

 larva is closely attached to the root by the caudal spines and 

 by the legs and with its head withdrawn into the thorax. From 

 numerous small glands all over the body is then secreted a 

 tough, sticky fluid, which covers the body as a thin mantle and 

 also spreads over the part of the root on which the larva sits. 

 While this outer cocoon is yet semifluid and elastic, the larva 

 stretches itself inside it and blows the cocoon up by air sucked 

 from the root, with the interior of which the larva is yet in 

 connection through the caudal spines. 



This outer mantle absorbs and carries with it all the dirt on 

 the larva, so that it lies clean and white within, filling about 

 one-half of the cocoon. 



The larva then begins to secrete from the mouth a varnish- 

 like fluid, which it smears around on the inside of the cocoon 

 by rubbing the head back and forth. During this work it finally 

 withdraws the caudal spines and turns around so as to apply 

 the varnish to all parts of the cocoon. 



If the larva is taken out of the cocoon at this stage the ali- 

 mentary canal is found to be much swollen and filled with a 

 clear honey-yellow matter, which Doctor I loving thinks is in 

 the main the accumulated excrement ; this content of the ali- 

 mentary canal is ejected from the anus and used to cover and 

 strengthen the bottom of the cocoon toward the root. The 

 cocoon thus finished the larva gnaws one or two holes through 

 the bottom into the air-cells of the root and thus reestablishes 

 the temporarily suspended respiration. 



The different species of Donacia gnaw one or two holes and 

 it is possible to identify the species from the position and 

 number of these holes alone. 



The larva then in time transforms to pupa and eventually to 

 adult. The length of the larval period covers two seasons. 



During, the writer's visit in Copenhagen, last fall, Doctor 

 Boving generously gave him, for the collections of the r. S. 

 Xational Museum, a fine set of the material on which hi-> 

 paper was based eggs, larvae, and cocoons in various stages, 

 adults, and work. 



-Mr. Schwarz said that in North America we have some 

 species of Donacia, especially of the subgenus Plateumaris, 

 which are evidently not aquatic in their habits, their larvae being 

 supposed to live in very wet ground on the roots of Sagittaria 

 and similar plants. Such larvae may differ somewhat in struc- 

 ture from those described by Doctor lloving. 



