248 The Ohio Journal of Science [Vol. XVIII, No. 7, 



the specialization of this structure, such other modifications as 

 the loss of wings and shortening of the antennae in the female — 

 all leading to sexual dimorphism — can be correlated. Thus, 

 as is shown in the above phylogenetic tree, we start with 

 Aphelopus as the most primitive and generalized group in which 

 there is no sexual dimorphism. We note specialization pro- 

 ceeding along two different lines : one a loss of wings, probably- 

 due to the general activity and abundance of the host; the 

 other a development of the chelate tarsus as an aid to catching 

 and holding the active prey. With the latter again specializa- 

 tion has taken place with regard to the kind of host attacked. 

 Perkins (1905) has observed that Anteonince parasitizing jassids 

 have the lateral claw of the chela without lamellae, and generally 

 curved, (Plate I, Fig. 7). Those confining their attacks to the 

 Fidgoridce having the lateral claw of the chela with lamellae, 

 generally nearly straight and with a slight notch near the tip, 

 (Plate I, Fig. 8). So characteristic is this structure of the chela 

 that the host family can be ascertained at once by examining 

 the female. 



Specialization has taken place primarily and more markedly 

 in the female, the males of even those species having the most 

 highly specialized females being very similar to the males of 

 the most generalized genus. This is due to the greater need for 

 activity on the part of the female in the hunting and capturing 

 of the active hosts. In fact, males of some of the more highly 

 specialized genera are still unknown and these species are 

 possibly entirely parthenogenetic. 



LIFE HISTORIES OF SPECIES. 



Gonatopus erythrodes (Perkins). 



July 3, 1917, a large number of Deltocephalus inimicus 

 nymphs bearing dryinid larval sacs were collected in a run-down 

 meadow near Castalia, Ohio. About thirty per cent of the 

 nymphs of this species were parasitized. They were placed 

 individually in shell vials for separate study. This field was 

 revisited several times on successive days, but after July 15 the 

 parasites had disappeared, the remaining nymphs having 

 matured. July 9 the first parasite killed its host, and July 17 

 the last one of the series of sixteen individuals collected had 

 entered the ground to pupate. 



