238 PROCEEDINGS OF THE NATIONAL MUSEUM vol. in 



the correct placements of niger Cole and hennigi, new species, seem 

 somewhat dubious. The richness of the fauna of this region is shown 

 by the presence of two of the three subgenera, and four of the six 

 species groups now recognized for the world. The pallidipennis 

 group predominates, with sabroskyi, new species, being the most highly 

 developed member. The four species of the colei group are all closely 

 related but actually represent two different stocks. In certain features, 

 vittisternum Sabrosky is quite similar to floridensis Sabrosky, while 

 colei Sabrosky is likewise somewhat similar to shewelli Sabrosky, 

 hence their position on the tree. The close approximation of melampus 

 Loew and eugonatus Loew is due to the possibility of then- being 

 conspecific (see discussion, p. 279). 



Biology 



Although acrocerid biology as a whole is scarce, more work has 

 been done on Ogcodes than all other genera put together. All known 

 species are solitary internal parasites of true spiders (Araneae) during 

 their larval stages. Since biological observations have been sum- 

 marized recently by Millot (1938), Clausen (1940), and Plomley 

 (1947b), a general outline sketch of my observations on several 

 species is all that seems to be required at this time. For further notes 

 on the habits of the particular species, see the discussion under the 

 appropriate species in the text. 



There are about 30 known host-parasite relationships for the genus 

 Ogcodes. Although most of the common hosts belong to the spider 

 family Lycosidae, the following families are also recorded as hosts: 

 Amaurobidae, Salticidae, Psechridae, Thomosidae, Anyphaenidae, 

 Clubionidae, Gnaphosidae, Agelenidae, and Theridiidae. For a 

 complete list of host-parasite relationships see table 1. 



Stein (1849) was the fii'st person to observe the habits of these 

 flies. Following him, the more important contributions were made 

 by Gerstaecker (1856), Maskell (1888), Giard (1894), Konig (1894), 

 Bovey (1936), Kaston (1937), Millot (1938), Dumbleton (1940), 

 Clausen (1940, summary only), Plomley (1947b), and Kessel (1948). 

 Of these works, those of Millot, Dumbleton, and Plomley are out- 

 standing. 



Oviposition: In all observed species, eggs are laid in great num- 

 bers, as many as 3,000 having been recorded for a single female during 

 a four-hour period. They are deposited singly, varying with the 

 species and time of day, from one every five seconds to about one 

 every minute. They are almost always laid on or near the apices of 

 dead twigs, and only rarely can they be found on growing plant parts. 

 Usually, females are found congregated on a twig, laying their eggs 



