138 PROCEEDINGti OF THE NATIONAL MUSEUM. vol. 5G. 



The species of Homalctylus are parasitic in Coccinellid larvae (some- 

 times issuing from the pupa), and two are known to attack Chryso- 

 melid larvae as well. They are, tlierefore, of prime economic impor- 

 tance and detrimental on tlie whole to the interests of agriculture. 



The species may be divided into three groups as follows: 



1. Ovipositor prominently protruded 2 



Ovipositor not protruded and hardly visible, except in distorted specimens. 



Flaminms group. 



2. Head considerably longer than wide, the vertex very narrow, the pin-punctures 



sometimes absent on the frontovertex Vidnus group. 



Head hardly or not at all longer than wide, the vertex comparatively wide, the 

 pin-punctures iisually well developed Cocherelli group, 



FLAMINIUS GKOU?. 



The forms of Homalotylus belonging to this group show a consider- 

 able amount of structural variation, within very narrow limits, how- 

 ever, and an even greater degree of coiorational variation, thus 

 presenting unusual difficulties in the way of their specific separation. 

 Leaving out of account small variations they seem to have great 

 structural stability, from within the narrow limits of which thay have 

 been unable to depart, and yet the group has great antiquity, as it 

 has become spread over all of the greater land masses of the earth. 

 Specimens from such widely separated regions as Europe, Australia, 

 South Africa, Asia, and North America exhibit only minor structural 

 differences, many of which seem to be more individual than geographic 

 in character. The variation in color although greater in extent seems 

 in some ways even less dependent on locality, yet it must be confessed 

 that some of the North and South American forms present by far 

 the greater range of departure from the normal type of coloration. 

 Leaving out of consideration these extreme American departures 

 from the typical scheme of coloration, the same minor variations 

 may be found in widely separated areas. 



On account of this stability in form and to a less extent in color, 

 coupled with a puzzling degree of variability, the writer has labored 

 under great difficulty in reaching any definite conclusion on the spe- 

 cific identity of certain forms, and has been obhged to reverse his 

 opinion several times as the study of the forms progressed. The final 

 conclusion, subject, however, to further revision if necessary, leaves 

 one Old World species and six ostensible American species in the 

 field, since the variation in the material examined seems to that 

 extent discontinuous. 



The writer has formed the opinion, however, that there are innu- 

 merable local races, probably to a large extent physiological, of 

 several of the species, some of them exhibitnig coiorational departures 

 from the usual type, others not, and perhaps in most cases breeding 

 true. In some localities there are apparently several of these races. 



