222 A YEAR OF COSTA RICAN NATURAL HISTORY 



would like, as it is based partly on memory; when I came 

 to write it down on returning to our cabin I found that the 

 caterpillar had begun the spinning of a cocoon in the box 

 in which I had placed it. On the following morning it had 

 completed its cocoon, using its own curious outer covering 

 to serve as the outer covering of the cocoon. 



Bag-worms do exist here, for on April 27 we found a num- 

 ber of small ones on a rock by the side of the Reventazon 

 road. Their cases were about one-third inch long and closely 

 resembled the lichens growing on the same rocks. Each 

 consisted of an outer oval or ellipsoidal case enclosing an 

 inner three-sided prismatic case, the latter containing the 

 minute caterpillar, 4 millimeters in length. Both cases were 

 of silk and both were open at each end; the inner was loosely 

 moored to the outer by a few strands of silk passing from the 

 three edges of the former to the inner surface of the latter. 

 After death at least, the hind end of the inner case projected 

 about one millimeter beyond the outer case. Attached to 

 the outer surfaces of both cases were some fragments of 

 plants such as seed-coats, chaff, an akene with its pappus, and 

 also chitinous parts of insects such as the heads of small 

 ants, prothoraces of beetles, wings and legs. Such cadaver- 

 ous booty is attached to their own silken cases by some neu- 

 ropteroid insects but is not often reported for lepidopterous 

 larvae, and it is difficult to imagine that the tiny builders 

 of these bags could overcome ants which must have been as 

 large as themselves. Can they obtain their trophies from 

 the dead which they find in the course of their wanderings.^ 

 We know nothing of the identity of these caterpillars, but 

 one thinks of the insectivorous habits recorded for some of 

 the tineids, the clothes' moth family. 



was found two months later in a badly battered condition. The fragment resembles 

 Ph. pithecium but is not identical; can it be Euryda variolaris of the Biologia Cen- 

 trali- Americana? 



