Hagen.] 324 [November 27, 



Haldeiuau (American Journal of Science, 2d Series, Vol. vi, p. 24) 

 writas of a parasitic Chelifer found under the Elytra of Alaus ocu- 

 laius : and in the London Magazine of Nat. Hist., Vol. iv, p. 94 and 

 V, p. 754, it is communicated anonymously that Chel. cancroicles is 

 often found parasitic on Diptera, principally on flies. 



In the same magazuie, Vol. iv, p. 283, these statements are doubted, 

 but were still maintained by Mr. Laxis. He reijeatedly found C/tel. 

 cancroirk'S and other species attached to the legs of Musca laroarum, 

 domeslica and meteorica, principally in hot weather. Mr. Clapton once 

 found four Chelifers attached to one leg of a fly. Another naturalist 

 has found Chel. cimicoides on Stomoxys calcitrans. The latter com- 

 munications arc repeated in Wiegman's Archiv, Vol. i, 2, p. 186, 

 with the observation that the Chelifer used the fly as a means of 

 changing his place of living. 



Many j-ears since I myself received three Chelifers from Venezuela 

 with the annotation, "found parasitic under the elytra of Acrocinus 

 longimanus." 



When I fii'st saw the fly given by Mr. Lyman I noticed but one 

 Chelifer, but by the aid of the microscope, I found another Chelifer 

 attached to the same leg. This was apparently a voyage en famille. 

 Why Chelifer should be attached to other insects is still unknown. 

 Of the opinion maintained by many authors, that this is an act of 

 parasitism, I have very great doubts. It is true that the Chelifer eats 

 by sucking, but it is very doubtful whether it would choose for its food 

 animals whose segments are very thick compared with the power of 

 the minute Chelifer. I think that the segments under the elytra of 

 Alaus oculatus and of the gigantic Acrocinus longimanus could never 

 be perforated by the very small and soft maxillary apparatus of the 

 Chelifer. The legs of the Flies are also too tough ibr its food, and the 

 Chelifers are always found attached to the legs and not to the softer 

 abdomen. Many authors have observed that Chelifer eats the little 

 Atropos pidsatorius (death watch), and this is probably suited to its 

 power and size. 



In consideration of these facts I think it more probable that the 

 opinion given in Wiegman's Archiv is correct; that the Chelifer used 

 these animals as an expeditious means of changing his location, that 

 he might find elsewhere more and better food. 



I am not quite certain of the systematical name of the species kindly 

 presented by Mr. Lyman. So flir as I know there exist but three 

 sjiecies described from America, two bj- Mr. Say, and one, constantly 

 overlooked, by Linne or De Geer. In the Journal of the Academy 

 of Natural Sciences of Philadelphia, 1821, i, p. 63, Say has described 

 Chelifer muricatu^ and Chelifer ohlongus. The first cannot be our 

 species, because Say says that the third joint of its palpi is nearly three 



