. ▁ ▁In sect s ▁are ▁not , ▁however , ▁the ▁ancest ral ▁form ▁of ▁the ▁other ▁ar th rop ods ▁discussed ▁here . ▁ ▁In sect s ▁ ▁In sect ▁mouth parts ▁exhib it ▁a ▁range ▁of ▁forms . ▁ ▁The ▁earliest ▁insect s ▁had ▁che wing ▁mouth parts . ▁ ▁Special isation ▁includes ▁mouth parts ▁modified ▁for ▁si phon ing , ▁pier cing , ▁su ck ing ▁and ▁sp ong ing . ▁ ▁These ▁modifications ▁have ▁evol ved ▁a ▁number ▁of ▁times . ▁ ▁For ▁example , ▁mos qu ito es ▁( which ▁are ▁f lies ) ▁and ▁a ph ids ▁( which ▁are ▁bugs ) ▁both ▁pier ce ▁and ▁su ck ; ▁however , ▁female ▁mos qu ito es ▁feed ▁on ▁animal ▁blood ▁whereas ▁a ph ids ▁feed ▁on ▁plant ▁flu ids . ▁ ▁This ▁section ▁provides ▁an ▁over view ▁of ▁the ▁individual ▁mouth parts ▁of ▁che wing ▁insect s . ▁ ▁Lab rum ▁ ▁The ▁lab rum ▁is ▁a ▁flat ▁extension ▁of ▁the ▁head ▁( below ▁the ▁c ly pe us ), ▁covering ▁the ▁mand ibles . ▁ ▁Un like ▁other ▁mouth parts , ▁the ▁lab rum ▁is ▁a ▁single , ▁f used ▁plate ▁( though ▁it ▁originally ▁was — and ▁emb ry on ically ▁is — two ▁structures ). ▁ ▁It ▁is ▁the ▁upper - most ▁of ▁the ▁mouth parts ▁and ▁located ▁on ▁the ▁mid line . ▁ ▁It ▁serves ▁to ▁hold ▁food ▁in ▁place ▁during ▁che wing ▁by ▁the ▁mand ibles ▁and ▁thus ▁can ▁simply ▁be ▁described