410 ENTOMOLOGICAL NEWS. [Nov., 



possible origin to have occurred, to the forest at Juan Vinas 

 where the trees which harbored our larvae were far, far above 

 the highest flood marks of the Rio Reventazon. M. modestus, 

 M. ornatus and Mcgaloprepus coernlatus, as we saw them in 

 Costa Rica, usually fly above the underbrush and when disturb- 

 ed, rise to a height of many feet above the ground. 



The excessively long abdomen of the adults of Mecistogaster 

 and its allies (Megaloprepus, Microstigma, Pseudo stigma,, Ano- 

 misma) may be a special adaptation to the life of their off- 

 spring in water-containing plants, since the abdomen of the lar- 

 va of M. modestus is no longer, proportionally, than in other 

 Agrioninse. The space between the leaf of a bromeliad and 

 the leaf next without decreases downward, and if Mecistogas- 

 ter's eggs are deposited in the plant tissue in or near the con- 

 tained water, in accordance with the general habit of the Zy- 

 goptera, it would often be necessary for the female to reach far 

 down into crevices possibly too narrow to admit of the en- 

 trance of her thorax and wings. The long abdomen with the 

 ovipositor near its hind end would therefore be of distinct ad- 

 vantage, and it will be a matter of great interest to ascertain, 

 by future observations, if the lengths of abdomens seen in va- 

 rious members of the legion Pseudostigma of de Selys are cor- 

 related with peculiarities in length in the plants or other ob- 

 jects in which they oviposit. 



(The larva and transformation of M. modestus will be described and 

 figured in Number III of these Studies.) 



Supplementary Note on Plant-dwelling Odonate Larvae. In addi- 

 tion to the records of plant-dwelling Odonate larvae already mentioned 

 in the NEWS (Calvert, 1910 b), Mr. Frederick Knab has called my 

 attention to a paper by G. F. Leicester (1903), containing the follow- 

 ing statements: "One of the most important breeding places [for 

 mosquitoes] in the jungle is the water which collects in the bamboo, 

 either in the stumps of old bamboo or in the cavities of fallen bamboos 

 which in some cases have cracked in drying and allowed water to ac- 

 cumulate in them, or even in standing living bamboos in which some 

 insect has bored a hole in the stem and allowed water to enter (p. 291). 

 * * * Other natural enemies [of mosquito larvae living in the same 

 places, in addition to the carnivorous mosquito larvae Megarhinus\ 

 are the larvae of certain species of Agrionidae, Libellulidae and Chir- 

 onomidae." (p. 292). 



