▁leaf - min ing ▁be et les ) ▁are ▁a ▁sub family ▁of ▁the ▁leaf ▁be et les , ▁or ▁Ch rys om el idae . ▁ ▁Description ▁The ▁" c ass ido ids " ▁have ▁a ▁rounded ▁outline ▁with ▁the ▁edges ▁of ▁the ▁pron ot um ▁and ▁el y tra ▁spread ing ▁out ▁to ▁cover ▁the ▁legs ▁and ▁head . ▁They ▁are ▁often ▁colour ful ▁and ▁met all ic , ▁with ▁the ▁ability ▁to ▁change ▁the ▁colour ▁( and ▁lost ▁in ▁spec im ens ) ▁which ▁is ▁present ▁in ▁the ▁living ▁t issue ▁below ▁the ▁transl uc ent ▁cut icle . ▁All ▁members ▁of ▁the ▁sub family ▁have ▁the ▁mouth parts ▁reduced ▁into ▁a ▁cav ity ▁in ▁the ▁head ▁caps ule , ▁the ▁legs ▁have ▁four ▁segment ed ▁tar si . ▁The ▁his po ids ▁have ▁lar va e ▁that ▁are ▁leaf ▁min ers , ▁while ▁the ▁c ass ido ids ▁feed ▁on ▁the ▁plant ▁surfaces , ▁sometimes ▁covering ▁their ▁bodies ▁with ▁fa ec al ▁shield s . ▁Although ▁f ec al ▁shield s ▁are ▁thought ▁to ▁provide ▁defense , ▁no ▁evidence ▁exists ▁for ▁such ▁a ▁role . ▁Some ▁Cass id ini ▁show ▁mat ernal ▁care ▁of ▁lar va e . ▁ ▁Tax onomy ▁It ▁includes ▁both ▁the ▁former ▁sub family ▁" H isp inae " ▁( leaf - min ing ▁be et les ), ▁as ▁well ▁as ▁the ▁former ▁more ▁narrow ly ▁defined ▁sub family ▁Cass id inae ▁( famil iar ▁as ▁tort o ise ▁be et les ) ▁which ▁are