organ isms . ▁Many ▁D ip tera ▁lar va e ▁are ▁pre dat ory , ▁sometimes ▁on ▁the ▁lar va e ▁of ▁other ▁D ip tera . ▁ ▁Many ▁Ag rom yz idae ▁are ▁leaf ▁min ers . ▁Some ▁Te ph rit idae ▁are ▁leaf ▁min ers ▁or ▁gall ▁form ers . ▁The ▁lar va e ▁of ▁all ▁O estr idae ▁o est rid s ▁are ▁oblig ate ▁par as ites ▁of ▁m amm als . ▁( O estr idae ▁include ▁the ▁highest ▁proportion ▁of ▁species ▁whose ▁lar va e ▁live ▁as ▁oblig ate ▁par as ites ▁within ▁the ▁bodies ▁of ▁m amm als . ▁Most ▁other ▁species ▁pr one ▁to ▁cause ▁my ias is ▁are ▁members ▁of ▁related ▁families , ▁such ▁as ▁the ▁Cal li ph or idae . ▁There ▁are ▁roughly ▁ 1 5 0 ▁known ▁species ▁world wide .) ▁T ach in idae ▁lar va e ▁are ▁par as it ic ▁on ▁other ▁insect s . ▁Con op idae ▁lar va e ▁are ▁end op ar as ites ▁of ▁be es ▁and ▁was ps ▁or ▁of ▁co ck ro aches ▁and ▁cal y ptr ate ▁D ip tera , ▁P yr got idae ▁lar va e ▁are ▁end op ar as ites ▁of ▁adult ▁scar ab ▁be et les . ▁Sci om yz idae ▁lar va e ▁are ▁exclus ively ▁associated ▁with ▁fresh water ▁and ▁terrest rial ▁sn ails , ▁or ▁sl ugs . ▁They ▁feed ▁on ▁sn ails ▁as ▁pred ators , ▁par as ito ids , ▁or ▁sc