Insects with backpacks. 1 Trichoptera: Caddisfly larvae in case (photograph: S. Marshall) 2 Trichoptera: Caddisfly larvae in case (photograph: S. Marshall) 3 Trichoptera: larva with its case, 1980–1994, gold, opal, pearls (case length = 1 inch; photograph: H. Del Olmo (from Hubert Duprat exhibition, ADAGP)) 4 Neuroptera: Chrysopidae: larva with exuvial debris (photograph: Masayuki Hayashi) 5 Hemiptera: Reduviidae: assassin bug, Singapore (photograph: Nicky Bay) 6 Hemiptera: Reduviidae, assassin bug, Costa Rica (photograph: Dieter Mahsberg) 7 Lepidoptera: Psychidae: caterpillar with its bag 8 Lepidoptera: Geometridae: Wavy Emerald Moth caterpillar, Synchlora aerata (Fabricius, 1798), covering itself with petals of its host, Liatris Gaertn. ex Schreb. sp. (Asteraceae) (photograph: Hope Abrams) 9 Lepidoptera: Nolidae: caterpillar of Uraba lugens Walker, 1866 with stack of their exuvial head capsules, Australia (photograph: Alan Henderson) 10 Coleoptera: Curculionidae, Gymnopholus Heller, 1901 weevil carrying lichen garden, Papua New Guinea (photograph: Adrian Tejedor) 11 Phasmida: stick insect, Trychopeplus laciniatus (Westwood, 1874), with exoskeleton modified to appear like moss, Costa Rica (photograph: Kenji Nishida) 12 Hemiptera: Membracidae with exoskeleton modified to appear like moss, Costa Rica (photograph: Kenji Nishida) 13 Coleoptera: Curculionidae: weevil larva retains moist faecal coat (photograph: Filip Trnka) 14 Coleoptera: Erotylidae: larva of Toramus Grouvelle, 1916 with shield of exuviae held on setae (photograph: Takahiro Yoshida) 15 Coleoptera: Cassidinae: Cassidini: larva of Microctenochira Spaeth, 1926 undetermined species with shield of exuviae only (photograph: Kenji Nishida).

Recent phylogenetic hypotheses of Chrysomelidae subfamily relationships, redrawn by L. Schletzbaum from original sources 16 Reid (2000) (morphology-based) 17 Gómez-Zurita et al. (2007, 2008) (sequence-based) 18 Nie et al. (2020) (sequence-based). Other chrysomelid hypotheses to compare are Farrell (1998), Hunt et al. (2007), and Zhang et al. (2018, 2022). These available hypotheses are based on less than 1% taxon sampling of clade diversity. Subfamilies in bold font exhibit major patterns of faecal-based constructions. Alticinae (flea-beetles) is now regarded as the tribe Alticini within Galerucinae, so the faecal-retaining Blepharida-group is recognized now within Galerucinae. Only a single species in Phola Weise, 1890 (Chrysomelinae) has been reported to retain faeces (Chen 1964, 1985) so it is not a major pattern.

Shields of larvae and pupae in four tribes of Cassidinae (Coleoptera: Chrysomelidae) 19 Hemisphaerotini: Hemisphaerota Chevrolat, 1836 20 Ischyrosonychini: Physonota Boheman, 1854 21 Cassidini: Agroiconota bivittata (Say, 1827) 22 Aspidimorpha sanctaecrucis (Fabricius, 1792) 23 Cassidini: undetermined sp. 1 24 Cassidini: undetermined sp. 2 from Africa, collected by C.S. Chaboo 25 Cassidini: undetermined sp. 3 pupa from Brazil, collected by D. Yanega 26 Cassidinae: Undetermined sp. 4 Costa Rica, collected by K. Nishida. Darkened sections = faeces. Redrawn by L. Schletzbaum from original sources or from specimens.

Faecal structures of larvae and pupae in Cryptocephalinae (Coleoptera: Chrysomelidae) 27 Adiscus taiwanus 28 Chlamisus sp. 1 29 Chlamisus sp. 30 Coenobius taiwanus 31 Cryptocephalus trifasciatus 32 Fulcidax 33 Neochlamisus 34 Lamprosomatinae. Redrawn by L. Schletzbaum from original sources.

Faecal-based coats of larvae in Criocerinae (shining leafbeetles). 35 Criocerinae sp. 1 36 Criocerinae sp. 2 37 Lema hexastigma. Redrawn by L. Schletzbaum from original sources.

Faecal-based structures and coats maintained by larvae in the Blepharida-group (Galerucinae: Alticini; flea beetles). 38 Blepharida sacra 39 Diamphidia sp. 40 Podontia sp. Redrawn by L. Schletzbaum from original sources.

Life history in Stolas cucullata (Boheman, 1862) (tribe Mesomphaliini) in Costa Rica 41 adult 42 female laying eggs 43 eggs, grouped but not in contact 44 neonate larvae resting on egg shell (photographs: K. Nishida).

Telescopic anus and shield of larva, Cassidini undetermined sp. 4 on Chione sylvicola (Standl.) W. C. Burger (Rubiaceae) in Costa Rica 45–48 anus at different positions 49 pupa, postero-dorsal view 50 pupa, dorsal view (photographs: K. Nishida).

Calyptocephala attenuata on the host, Smilax domingensis Willd. (Smilacaceae), Monteverde, Costa Rica 51 larva with shield of five exuviae, dating this as instar VI 52 dorsal view 53 showing exuviae folded to expose head capsule and caudal processes 54 teneral instar II larva has just exited exuvia I and is retaining it on elaborate paired caudal processes (photographs: K. Nishida) 55 instar I (~ 42 mm long), showing caudal processes 56 instar I caudal processes (photographs: CS Chaboo) 57 adult partially exiting pupal exuvia, fronto-lateral view 58 adult partially exiting pupal exuvia, frontal view (photographs: K. Nishida).

Unidentified genus, 5^th instar larvae of Spilophorini on orchid host in Ecuador 59 mature larvae feeding in a group; note color contrast which may be aposematic and the leaf fragment on shield of one larva 60 single larva, dorsal view, with shield of four exuviae. Note exuvial folding exposes the anus and head capsule. Bases of caudal processes are also exposed (photographs: E. Schulz).

Timing of moulting process and exuviae retention in Calyptocephala attentuata. 61 at 17 seconds. Instar I larva lacks the shield 62 at 7 mins, instar II exiting from instar I exuvia 63 at 8 mins, the old head capsule is folded caudad, the instar II pulls forward, pushing the exuvia posteriad 64 at 13 mins, instar II larva with exuvia of instar I on urogomphi. Other instars with additional exuviae (drawn by L. Schletzbaum; timing follows films (Yamamoto 2018, 2020).

Life stages of Cassida sphaerula Boheman, 1853 (Cassidini) 65 instar I, neonate 66 instar II, with faeces on caudal processes 67 mature larva with faeces + exuviae shield 68 pupa with entire larval shield (faeces + exuviae) 69 pupa with shield comprised of only 5^th instar exuvia 70 adult (photographs: S. Adam, September 2021).

Re-construction of faeces on exuvio-faecal shield in Experiment 1, starting with instar I larva (so no prior exuvia), Cassida sphaerula Boheman, 1853 (Cassidini; photos: S. Adam, September 2021) 71 instar 1 (~ 2 mm long) at time 0 when faecal shield is removed, exposing urogomphi 72 larva at two hours, small faecal blob at anus 73 larva at four hours, urogomphi encased in faeces 74 larva at six hours, urogomphi encased in faeces 75 larva at 23 hours, lateral view. 76 larva at 48 hours, dorso-ventral view (photographs: S. Adam, September 2021).

Re-construction of faeces on exuvio-faecal shield in Experiment 2 with Cassida sphaerula Boheman, 1853 (Cassidini) 77 instar I (~ 2 mm long) before shield construction 78 instar II at time 0 with faeces removed (scraped off) 79 after 2 hours, dorsal view 80 after four hours, dorsal view 81 after 23 hours 82 after 48 hours (photographs: S. Adam, September 2021).

Faecal re-construction in experiment 3 with instar II larva, Cassida sphaerula Boheman, 1853 (Cassidini) 83 time 0 when faecal shield is removed, exposing instar I exuvia 84 larva at two hours, exuvia I still exposed 85 larva at four hours, faeces attached to lateral projections (scoli) of exuvia I 86 larva at six hours, exuvia I with a lot of faeces (photographs: S. Adam, September 2021).

Shield of pupa of Cassida sphaerula Boheman, 1853 (Cassidini) 87 host leaf chewed by beetles, with one larva and two pupae (dorsal views; upper one with exuvio-faecal shield; lower one with exuviae-only shield) 88 posterior view showing exuvial-faecal shield (of instars I–IV) attached to caudal processes of instar V exuviae 89 ventral view showing complete instar V exuvia and exuvio-faecal shield (photographs: S. Adam, September 2021).