204 BR. J. ENT. NAT. HIST., 13: 2001 



in the final nymphal stage. Thus for an individual having a total of N nymphal stages 

 the last two can be recognised by this character alone and denoted as stages N-l and 

 N even though the numerical value of N may be unknown. 



Although not forming part of the study as originally planned, a further rearing 

 trial on nymphs hatched in captivity was undertaken to supplement the information 

 obtained from this. 



Sites studied 



A. South Croydon: An area where, a few years previously, topsoil had been replaced 

 over tipped domestic refuse, and the vegetation allowed to regenerate naturally. 

 Here C. brunneus was clearly dominant, although occasional specimens of 

 C. parallelus occurred, probably as vagrants from nearby established grassland. 



B. South Croydon: Disused railway sidings and adjacent abandoned allotments. 

 C. brunneus was the only grasshopper found. 



C. Mitcham Common, London Borough of Merton: A mosaic of grassland types, 

 where C. parallelus was more conspicuous than C. brunneus, while other species 

 of grasshopper were also present. 



Experimental 

 Site A 



In 1969, 41 male and 52 female nymphs were collected, of which 22 and 31 

 respectively were retained for at least one moult. These were housed singly in 1-lb 

 jam-jars, the metal closures of which were lodged in place without being screwed 

 home. Grass cut from an untreated and unmown garden plot was supplied for food, 

 and the jars thoroughly cleaned, every two days. The jars were kept at ambient 

 indoor temperature, placed in the sun for an hour or so each day, but given no 

 artificial irradiation. Humidity was probably higher than desirable, some beads of 

 condensed moisture usually being present in the upper parts of the jars. For the final 

 stage the nymphs were transferred singly to 2-lb jars with loose-fitting metal covers; 

 these provided somewhat less humid conditions. All nymphal casts were retained as 

 physical evidence of moulting. 



The lengths of the hind-femora were recorded upon capture and after each moult. 

 The insects were immobilised by being placed for a few minutes in the freezing 

 compartment of a domestic refrigerator, and measurements made by direct 

 comparison with a glass scale engraved in millimetres and tenths, laid above and 

 in contact with the femur and viewed at x 16 with a stereomicroscope. 

 Measurements of hind-femora detached from nymphs that died indicated that this 

 procedure was sound. Furthermore, measurements of the hind-femora of nymphal 

 casts, if detached without damage to the basal end, were identical with live 

 measurements in 67 comparisons, 0.1 mm different in 53, and 0.2 mm different in 9, 

 the larger differences being confined to the later stages. In no instance did the 

 discrepancy exceed 4% and occasionally a cast measurement was used when a moult 

 occurred before a live measurement could be made. 



The stage at which wing-reversal occurred was noted, and nymphs with reversed 

 wings identified with stages N-l or N. Some counts of antennal segments were made 

 during life, but a much more detailed study of the antennal sheaths detached from 

 the retained casts was made later. Many complete sequences of the latter were 

 prepared for microscopic examination (Collins, 1988) to determine the pattern of 



