Orthoptera and allied insects of Essex 2003
Fig. 1: Density per m2 of adults of two Chorthippus species at Joyce Field
Year
Phenology
In addition to recording the abundance of two Chorthippus species, the author noted down the first
and last date that the stridulation (or song) of four common Orthoptera species was heard on the
Writtle College Estate during 2003 and compared this with the 2002 dates. Mature male adults
sing to attract females for mating (Baldock 2000). Therefore, recording the dates of the first and
last stridulation heard provides useful data on the speed of nymphal development. Orthoptera may
be a useful indicator of climate change (Burton 2001), as warmer weather during May and June
may lead to earlier maturity.
Both C. albomarginatus and C. parallelus were heard singing on 14th June in 2003, a remarkable
17 days earlier than in 2002 for the former species (Table 2). It was reported that Roesel's Bush-
cricket Metrioptera roeselii was heard singing on 30th June 2001 from Bushey Park, Surrey. This
species was singing on 3rd July at the Lee Valley Regional Park in the same year (Widgery 2001).
At Writtle, this species was first heard singing on 24th June in 2003. which is 15 days earlier than in
2002. The much earlier maturation of all four species in 2003 may be due to due high incidence of
solar radiation (Table 1) and high temperatures in April and May.
Table 2: The dates of the first stridulations heard on the
Writtle College estate (TL6707) by the author in 2002 and 2003
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Essex Naturalist (New Series) 21 (2004)