8o A YEAR OF COSTA RICAN NATURAL HISTORY 



brilliant in contrast to the afternoon mist or rain, we found 

 many insects flying over the pools and submerged parts 

 of this lane. Beautiful Syrphids hovered over the flowers, 

 their gorgeous colors looking wonderfully gem-like. They 

 are bright green above, the green melting into a vivid dark 

 blue while beneath, the green turns in certain lights to a 

 rich copper-red. As the insect hovers in one place for some 

 minutes, then darts off to another spot and hovers again, 

 the wings, like a humming-bird's, vibrating so rapidly that 

 the fly seems to hang motionless, all these colors shine and 

 glow so that the little creature is fairly dazzling. It is 

 Volucella obesa, a species found from Florida and New Mexico 

 to Chile, and in the East Indies; its body is ii millimeters 

 long, its wing-spread 24 millimeters. The wings have a 

 brown spot on the front edge at a little beyond mid-length, 

 not reaching halfway across the wing and a brown dot 

 also on the front edge a little before the wing-tip. 



The "bloody ditch" harbored quite a varied fauna. On 

 June 17 P. dredged up some snails, a few small fishes (not 

 over two inches), leeches, a large number of black or 

 sand-fly larvae (Simuliidae), dragonfly larvae, and many 

 individuals of the bug Deinostoma dilatatum an inch long. 

 These last are interesting on account of the habit of carrying 

 the eggs — to the number of twenty to a hundred — on the 

 back. The eggs stand side by side and are attached by 

 their tail ends, for when the time of hatching approaches 

 two dark spots indicating the eyes of the young may be seen 

 under the shell of that end of the egg which is toward the 

 observer. We took one of the egg-bearing bugs indoors 

 and kept it in a glass of water; some of the eggs hatched and 

 the young at once swam actively around in the water, but 

 the parent died before more than seven or eight of the eggs 

 had hatched. On other days we found two kinds of frogs 

 in our net. We wondered whether the leeches were able 



