1921.J 79 



ON NABIS LATIVENTRIS Boh. (HEMIPTERA-HETEROPTERA). 



BY E. A. BUTLER, B.A., B.SC, F.E.S. 



{Co)icluded from p. 61.) 



There are probably two other intermediate instars besides those 

 above described, the last two of which are probably the third and fifth. 

 'J^he fourtli is very darlc in colour, has the spines very well developed, and 

 shows the rudiments of the wing-pads. But from what has been said, 

 it will be evident that the larval changes consist of a good deal more 

 than the very necessary ones of mere alteration in size and acquisition of 

 wings. As already stated, there is no trace in the adult of the various 

 spines tliat, blunt or otherwise, appear in different jsarts in the successive 

 larval instars, and attain their maximum development when the insect is 

 about half grown ; it has been shown also that there is considerable 

 change in the hairy equipment of the legs ; some of these are merely 

 temporary organs, altogether discarded when the insect matures, while 

 others appear modified in both form and texture. One cannot but 

 conclude that they are of some importance to the welfare of the insect, 

 and it becomes an interesting question what their pi-ecise purpose and 

 significance can be. Some of the spines are rather suggestive, in a 

 profile view, of those on the propodaeum of an ant, but the correspondence 

 is not very exact, as they are more numerous, some are paired and some 

 single, and they are appended to a different part of the body. It is a 

 further interesting question why this species alone has larvae showing 

 superficial resemblance to ants and therefore entirely unlike those of the 

 rest of the genus, although the adult very closely resembles in form and 

 appearance one of the other species (J^. ajjferus), and is not widely 

 different from several others. By systematists, this species is included 

 in the same subgenus as iV. apteriis F. and iV. major Costa, an 

 arrangement which is certainly not supported by the larval forms, since 

 all three of them are of different types of structure. 



The larvae are abundant in July and August, maturing, as a rule, 

 towards the end of the latter month. The adult has been found from 

 January to November, so that evidently the species passes the winter as 

 an imago ; and those specimens which appear in the early months of the 

 year, and in fact up to late July or August, are the produce of 

 the summer of the preceding year. The life of the individual would seem 

 to last, as a maximum, for about 15 months. But no details are available 

 as to the date of oviposition. According to Morley ( " Hemiptera of 

 Suffolk " ), the insects copulate freely in captivity. 



