300 ENTOMOLOGICAI. NEWS. [J^ly, '15 



a means of transportation that goes a long way to explaining the sud- 

 den appearance of large numbers of diatoms in new localities, 



I therefore look upon this rather abundant flora on the minute leg 

 of this aquatic insect as of some scientific importance. Of course, in 

 this case the power to fly does not exist until a later period of develop- 

 ment, but many of the water beetles and other insects are doubtless 

 coated with living diatoms in the same way. 



A reference to Van Heurck's Treatise on the Diatomaceae 

 (English translation by Baxter, London, 1896) shows that 

 most of the diatoms listed above, and especially those of most 

 frequent occurrence, are "common everywhere," at least 

 throughout Europe and, as they occur in Costa Rica also, prob- 

 ably throughout the world. It is of interest, moreover, to 

 compare the data on the diatoms found attached to Thauma- 

 toneura larvae with those relating to the diatoms enumerated, 

 as occurring on the nymphs of various Odonata of the United 

 States, by Miss Lyon in the News for January, 191 5, pp. 4-6. 



Description of the Larvae. 

 Material Studied. Larvae in alcohol: 



(c) From hanging roots in farther waterfall, Juan Vinas, 3300 feet 

 (1000 metres), June 26 and 27, 1909. Nos. i, 2, 4 and 5, males, No. 3, 

 female. (For No. 4, see PI. xi., figs. 2, 3.) 



(&) From nearer waterfall, Juan Vitias, 3400 feet (1036 metres), 

 March 23 and 26, 1910. Nos. 6 to 8, females. (For No. 8, see PI. xi, 



fig. I.) 



(c) From the same waterfall, April 24, 1910. No. 9, $. 



[All of these died in attempted rearing. The following Thaumato- 

 neura larvae are recorded in our rearing list and, as there is no entry 

 of their having died, were presumably lost in the earthquake at Car- 

 tago. May 4, 1910:* No. 76 (one), No. yy (one). No. 78 (two) all from 

 the nearer waterfall, Juan Vinas, March 26, 1910.] 



Exuviae : 



9 Nearer waterfall, as above, Aug. i, 1909. 



$ inopinata same locality. April 26, 1910. (Watched in transforma- 

 tion. 



$ pellucida same locality, April 26, 1910. (Watched in transforma- 

 tion.) 



17 $ $ , g 9 9 same locality, April 24 and 26, 1910, in various 

 degrees of preservation. 



♦ See Ent. News, xxi, p. 336. July, 1910. 



