Yes, that is the larva. It is too late to treat the larvae; professional grape growers do not recommend treatment until more than 5% of crop is affected by the beetles. Very important to clean area in the fall and possibly disc area to prevent reinfestations next year. See the following website for identification: https://entomology.ca.uky.edu/ef224 The second website gives info on identification and treatment. See: https://ohiograpeweb.cfaes.ohio-state.edu/sites/grapeweb/files/imce/Insect_factsheet_Photos/Grape%20Flea%20Beetle.pdf The third website discusses control measures. In general no treatment is recommended unless more than 5% of leaves are affected. There is a table of chemical possibilities; not all may be available to home gardeners. See: https://c.ymcdn.com/sites/mngrapegrowers.site-ym.com/resource/resmgr/Growing_Grapes_in_MN_Best_Practices/Chapters/Ch_13_Insect_Pests_of_Grapes.pdf