NO. I BLACK FLIES OF GUATEMALA — DALMAT 367 



Atlantic watershed. The collections were made at altitudes of 1,500 

 feet and 5,000 feet. At the point of collection, the Rio Sokcha was 

 39 inches wide, 3 to 15 inches deep, with a current of 20 inches per 

 second; the temperature was 20° C. and the pH, 7.2. The collections 

 were both made during the month of November, at the beginning of 

 the dry season. Other species found developing in the same streams 

 were 6^. (S.) metallicum, S. (L.) samboni, S. (S.) ochraceum, and 

 S. (L.) dozvnsi. 



Simulium (Lanea) colvini Dalmat. — This species has been found 

 at an altitude of 260 feet in only one stream (name unknown) between 

 Malacatan and Ayutla, Department of San Marcos, near the Rio 

 Suchiate which divides Guatemala from Mexico. The larvae and 

 pupae were found on narrow leaves, approximately i inch beneath 

 the surface of the water. Other species that were found in the same 

 stream were 5^. {D.) pulverulcntimi, S. {S.) metallicum, and S. (L.) 

 downsi. 



Simidium (Lanea) dugesi Vargas, Martinez, and Diaz. — The pupae 

 of this species were found only once in a single stream, Rio Limon, 

 Escuintla. They were collected at 1,050 feet altitude, at a part of the 

 stream having a width of 15 feet; depth, 12 inches; temperature, 

 24° C. ; current (velocity), 2^ inches per second (290 gallons per 

 second) ; pH, 7.0. The river bed was sandy, with small and large 

 stones, and with few plants. The breeding area was open to the sun. 

 The collection was made at the beginning of the dry season. Other 

 species collected in the same part of the stream were 6". (D.) pulveru- 

 lentum, S. (L.) dozvnsi, S. (N.) exiguum, and .S. {S.) metallicum. 



Simulium (Lanea) jacobsi Dalmat. — The stream in which this larva 

 was found had a pH of 7.6, temperature of 26° C, current speed of 

 4I feet per second and volume of 3,130 gallons per second. The width 

 of the stream was approximately 42 feet, its depth 2 feet. Its bed was 

 composed of sand with numerous large and small stones, and with very 

 little emergent or trailing vegetation. The altitude of the region was 

 4,000 feet. The larva was collected from a twig floating on the surface 

 of the water. The collection was made in June, during a lull in the 

 rainy season. 



Simulium {Lanea) trivittatum Malloch. — The pupae of this species 

 were collected in the Department of Alta Verapaz, in a single stream 

 located on the northern slope of the Chuacus-Minas-Mico range 

 which forms the most northern chain of mountains in Guatemala. 

 The altitude of the region is about 4,600 feet. The river was about 

 5 to 10 feet deep, with crystal-clear water and with little to no 

 trailing vegetation; the current was swift, but with few rapids. The 



