I need a realistic picture of a cricket for school

(I hope you mean cricket the insect, and not the sport)

Have you tired Google?

Cricket + insect - Google Images (http://images.google.com/images?hl=en&rls=gm&sourceid=gmail&um=1&sa=1&q=Cricket+%2B+insect&aq=f&oq=&aqi=g1&start=0)

Just disregard the cartoon crickets.