The chirp -LRB- which only male crickets can do -RRB- is generated by raising the left hind leg to a NUMBER@1 degree angle and rubbing it against the right hind leg edge of the right hind leg , which has a thick scraper -LRB- PERSON@1 NUMBER@2 -RRB- .

The chirp is made by raising their left forewing to a NUMBER@1 degree angle and rubbing it against the upper hind edge of the right forewing , which has a thick scraper -LRB- PERSON@1 NUMBER@2 -RRB- .
