Inachis Research Articles

Increased mortality of isolated first instar larvae ofInachis io(Lepidoptera)

The European peacock butterfly, Inachis io Linnaeus is one of those lepidopteran species whose larvae stay together after hatching. Larvae usually aggregate in batches of hundreds. Isolated first instar larvae, although spin or feed to some extent, spend most of their time apparently waiting for a signal yet unknown for continuation, and finally end up dying until the second moult. In our experiments the mortality of isolated larvae varied significantly from 25% to 75%, indicating that loneliness induces a kind of death signal of unknown origin in first instar larvae of I. io .

SELECTION TOWARD SHORTER FLOWERS BY BUTTERFLIES WHOSE PROBOSCES ARE SHORTER THAN FLORAL TUBES

Darwin's meticulous observations on the function of floral shape led to his famous prediction of a long-tongued pollinator, which he believed to be the evolutionary trigger for the long-spurred flowers of the Madagascar star orchid. Although tubular flowers are common, long tubes or spurs are an exception, suggesting that selection maintaining short flowers is widespread. Using the butterfly-pollinated carnation Dianthus carthusianorum and two butterfly species differing in proboscis length (Melanargia galathea and Inachis io) as model organisms, we experimentally demonstrate a reduction in pollinator efficiency with an increasing difference between proboscis length and floral tube length. Such a relationship is a prerequisite for the evolution of floral shape in response to pollinator morphology.

Placing butterflies on the map – testing regional geographical resolution of three stable isotopes in Sweden using the monophagus peacock Inachis io

Stable isotope analyses of tissues have been used to help delineate natal regions and routes of migratory animals. The foundations of such studies are isotopic gradients or differences representing geographic regions and habitat used by the organism that are retained in selected tissues. We sampled peacock butterflies Inachis io on a regional level in southern Sweden to study natural variation and the resolving power of the stable isotope method to delineate individuals from known areas on a smaller scale than has typically been used in previous studies. Hydrogen (δD), carbon (δ13C) and nitrogen (δ15N) isotopes were obtained from butterflies at seven different locations in an area of 250×250 km over three years (2002–2004). We found sufficient isotopic differences on this regional scale to delineate approximate origins. Of the three isotopes, deuterium showed good discrimination between sites, carbon isotopes showed weaker differentiation, whereas nitrogen isotopes proved unsuitable for small scale studies in this region due to high and unpredictable variation. We found there was enough variation in δD between years to prevent a general application of the technique to resolve sub‐regional variation. Substantial part of this variation was probably caused by seasonal changes in δD of precipitation. These differences produce significant variation in δD between years in animals having short and variable tissue development times, and are difficult to estimate in natural situations. We conclude that stable isotopes are potentially powerful predictors for studies of migratory butterflies in Europe. However, without good knowledge about the sampled individuals’ previous life‐history, a lot of the natural environmental variation in tissue δD cannot be controlled for. In the case of migratory species, this information is difficult to obtain, making the confidence intervals for prediction of natal areas fairly wide and probably only suitable for longer distance migration.

Butterfly inclusions in Van Schrieck masterpieces. Techniques and optical properties

Dutch painter Otto Marseus Van Schrieck (1619–1678) is famous for his invention of “sottobosco”. These specific still-life paintings are characterized by the presence of various living organisms (mainly insects and plants) directly on the canvas. We will focus our attention on the painting kept in the museum of Grenoble, France, where a real butterfly is pasted on the canvas. The actual butterfly is a common Nymphalidae, Inachis io, presented in a static position on the dorsal side, without any perspective, compared to the neighboring butterflies. The colors of this butterfly are mainly due to pigments, melanin (black to brown) and ommochromes (yellow, orange, red) often in granules configuration that introduce scattering of light superimposed to the classical selective absorption, except in the ocelli of the hind wings where the blue coloration is due to interferential effects.

Rodent predation on hibernating peacock and small tortoiseshell butterflies

Insects that hibernate as adults have a life span of almost a whole year. Hence, they must have extraordinary adaptations for adult survival. In this paper, we study winter survival in two butterflies that hibernate as adults and have multimodal anti-predator defences—the peacock, Inachis io, which has intimidating eyespots that are effective against bird predation, and the small tortoiseshell, Aglais urticae, which does not have an effective secondary defence against birds. We assessed predation on wild butterflies hibernating in the attic of an unheated house, as well as survival of individually marked butterflies placed by hand on different sites in the attic. Our objectives were to assess (1) the number of butterflies that were killed during hibernation, (2) whether survival differed between butterfly species, and (3) how predation was related to hibernation site and the identity of the predator. There was a strong pulse of predation during the first 2 weeks of hibernation: 58% of A. urticae and 53% of I. io were killed during this period. Thereafter, predation decreased and butterfly survival equalled 98% during the final 16 weeks of hibernation. There was no difference in survival between the two butterfly species, but predation was site-specific and more pronounced under light conditions in locations accessible to a climbing rodent, such as the common yellow-necked mouse, Apodemus flavicollis. We contend that small rodents are likely important predators on overwintering butterflies, both because rodents are active throughout winter when butterflies are torpid and because they occur at similar sites.

Efectos de reserpina y p-cloranfetamina en el metabolismo y la liberación de 5-HT en el ganglio cerebral de Inachis io (Lepidoptera).

There have been few pharmacological studies of serotonergic system dynamics in insects. A more precise knowledge of the response of serotonergic neurons to drugs will contribute to understanding of the role of this neurotransmitter in insect behaviour. The present work was carried out to study several aspects of serotonin (5-HT) metabolism and release in an insect, the butterfly Inachis io. The effects of a single intra-abdominal injection of reserpine (30 pg/insect) or p-chloroamphetamine (50 microg/insect) on cerebral ganglia 5-HT metabolism and release were studied. After reserpine injection a depletion of 5-HT stores concomitant with an increase in N-acetylserotonin levels was observed, but not significant alteration of extraneuronal 5-HT release was observed. Administration of p-chloroamphetamine (PCA) induced extraneuronal 5-HT release, together with inhibition of its reuptake. Finally, a single injection of p-chloroamphetamine in reserpine-treated insects was able to induce new release of 5-HT. Reserpine interferes with the vesicular storage of 5-HT, but does not affect the process of neuronal release, while PCA induces the synaptic release of 5-HT and inhibits its reuptake. These effects are similar to those observed in mammals.

“An eye for an eye?”—on the generality of the intimidating quality of eyespots in a butterfly and a hawkmoth

Large eyespots on the wings of butterflies and moths have been ascribed generally intimidating qualities by creating a frightening image of a bird or mammal much larger than the insect bearing the eyespots. However, evidence for this anti-predator adaptation has been largely anecdotal and only recently were peacock butterflies, Inachis io, shown to effectively thwart attacks from blue tits, Parus caeruleus. Here, we test whether large eyespots on lepidopterans are generally effective in preventing attacks from small passerines and whether the size of insect or bird can influence the outcome of interactions. We staged experiments between the larger eyed hawkmoths, Smerinthus ocellatus, and the smaller peacock butterflies, I. io, and the larger great tits, Parus major, and the smaller blue tits, P. caeruleus. Survival differed substantially between the insect species with 21 of 24 peacock butterflies, but only 6 of 27 eyed hawkmoths, surviving attacks from the birds. Thus, surprisingly, the smaller prey survived to a higher extent, suggesting that factors other than insect size may be important. However, great tits were less easily intimidated by the insects’ eyespots and deimatic behaviour and consumed 16 of 26, but the blue tits only 8 of 25, of the butterflies and hawkmoths. Our results demonstrate that eyespots per se do not guarantee survival and that these two insects bearing equally large eyespots are not equally well protected against predation.

The proximate control of pupal color in swallowtail butterflies: Implications for the evolution of environmentally cued pupal color in butterflies (Lepidoptera: Papilionidae)

The environmentally cued production of cryptic green/yellow or brown/melanized pupae is widespread in butterflies, occurring in the Nymphalidae, Pieridae, and the Papilionidae subfamily Papilioninae. The dimorphism is controlled by the hormone pupal melanization reducing factor (PMRF). In the nymphalid Inachis io dibutryl cAMP mimics PMRF, and inhibits pupal melanization. However, in the papilionid Papilio polyxenes PMRF stimulates browning, suggesting that the control of pupal color by PMRF has evolved independently in the swallowtail and nymphalid–pierid lineages. We examined this hypothesis by using ligatures to prevent hormone release in five species representing three Papilioninae tribes. One species, Papilio glaucus, produces only brown pupae. Ligatures resulted in green cuticle posterior to the ligature in all five swallowtail species, including P. glaucus, suggesting that the mode of action of PMRF is the same in the three tribes. We also found that in P. polyxenes injections of dibutryl cAMP into prepupal larvae mimic the effect of PMRF, by causing dose-dependent pupal browning. Our results support the hypothesis that the control of pupal color by PMRF has evolved independently in the two lineages. The observation that green pupal color can be induced in P. glaucus by ligature indicates that environmentally cued pupal color could evolve by facultative inhibition of PMRF release.

EYESPOT FEAR FACTOR

Toward the end of cartoonist Gary Larson's There's a Hair in My Dirt (1998), the hapless protagonist, Harriet, is momentarily frightened by “a pair of large, ominous eyes staring back at her. `Oh, I recognize you now, Mr. Owl!' she laughed.” Larson's comment: “Ha! Did Harriet ever get taken in by one of the oldest tricks in Nature's book –the old I'm-a-scary-creature-with-giant-eyeballs gag. You see, `Mr. Owl' was really a Royal moth, an insect that uses its large wingspots to mimic a much more frightening animal.” Though widely accepted in common lore, how well do eyespots actually protect real Lepidoptera? Save a few older studies,notably one by Blest in 1957, remarkably little is known.Enter Adrian Vallin and colleagues, with an elegant demonstration of the eyespot fear factor. They studied whether eyespots defend peacock butterflies(Inachis io) against foraging blue tits (Parus caeruleus). Peacock butterflies at rest depend on crypsis – holding their wings folded above the body, so that the ventral sides, which mimic leaves, show. But crypsis can fail, and when it does the butterfly opens its wings to reveal ventral eyespots embedded in a background of bright colors. Simultaneously, it emits a hissing noise and two clicks, manufactured by rubbing fore- and hindwing veins together.Vallin and colleagues analyzed the anti-tit effectiveness of eyespots and hissing alone and in combination, using an old and effective set of tools:scissors and a black permanent marker. They created eyespotless butterflies by coloring over the four eyespots and created controls by blacking out other wing areas. To create non-hissing butterflies, the authors cut off the lower margin of the forewings, and they removed the lower margin of the hindwings to create controls. On a final set of butterflies, the authors removed both devices and constructed appropriate control individuals.The authors placed each butterfly, experimental or control, in a sparsely furnished room (willow log for the butterfly, perch for the bird). They set room temperature low enough to prevent butterfly flight but not so low that they were immobilized. Blue tits invariably found their intended victims, but whether or not they killed them depended almost entirely on whether or not the butterfly had eyespots – indeed, combining groups, only one of 34 butterflies with eyespots was killed, whereas 13 of 20 with covered eyespots were killed. Butterflies waited until birds were close, or even touching them,before flashing their wings. Those with intact eyespots were able to scare birds away repeatedly. Surprisingly, sound production had no discernible additional effect.So it's true: the flash-some-scary-eyeballs gag really seems to work. But it would be premature to announce case closed. Why do peacock butterflies produce sound? Perhaps it magnifies the effects of eyespots in other more natural contexts or against other attacking predators. Which and who? Also,why are blue tits so easily conned? Fright-and-flight makes sense the first time a blue tit is flashed, but shouldn't the bird rapidly see through the ploy? Perhaps the bird-brain circuitry engaged in procuring the next meal is completely overruled by a fright reflex stemming from one of the most important and ancient of rules: eyeballs portend gullets. Butterfly eyespots only pretend gullets, but that's enough.

Landscape Resources for the Territorial Nymphalid Butterfly Inachis io: Microsite Landform Selection and Behavioral Responses to Environmental Conditions

We investigate the use of landforms at different scales by males of the territorial nymphalid butterfly Inachis io (Linnaeus, 1758) under different weather conditions. They are known to use landforms at two different scales including macroscale, such as valley sides, tops of slopes and wood edges, and mini-landforms, such as molehills produced by the burrowing animal Talpa europaea Linnaeus (Linnaeus, 1758). Here, we demonstrate that they exploit microscale features on the molehills. The butterfly shifts its position in the landscape in relation to changing conditions by flying, and at the microscale, by walking. The links between thermoregulatory behavior and site selection indicate that perches are adopted to maintain body heat in the cool spring conditions when territories are established. Mini-landforms such as the molehills are adopted for their potential shelter and warmth in relation to ambient conditions; microsite selection typically includes warm niches on molehills, such as sunny slopes, sheltered margins and depressions. Shelter is adopted regardless of reduced visibility for territorial males. The importance of non-consumable (mate location) resources at different spatial scales is discussed in the context of habitat and the matrix.

Prey survival by predator intimidation: an experimental study of peacock butterfly defence against blue tits

Long-lived butterflies that hibernate as adults are expected to have well-developed antipredation devices as a result of their long exposure to natural enemies. The peacock butterfly, Inachis io, for instance, is a cryptic leaf mimic when resting, but shifts to active defence when disturbed, performing a repeated sequence of movements exposing major eyespots on the wings accompanied by a hissing noise. We studied the effect of visual and auditory defence by staging experiments in which wild-caught blue tits, Parus caeruleus, were presented with one of six kinds of experimentally manipulated living peacock butterflies as follows: butterflies with eyespots painted over and their controls (painted on another part of the wing), butterflies with their sound production aborted (small part of wings removed) and their controls, and butterflies with eyespots painted over and sound production aborted and their controls. The results showed that eyespots alone, or in combination with sound, constituted an effective defence; only 1 out of 34 butterflies with intact eyespots was killed, whereas 13 out of 20 butterflies without eyespots were killed. The killed peacocks were eaten, indicating that they are not distasteful. Hence, intimidation by bluffing can be an efficient means of defence for an edible prey.

Mating system and the evolution of sex-specific mortality rates in two nymphalid butterflies.

Life-history theory predicts that organisms should invest resources into intrinsic components of lifespan only to the degree that it pays off in terms of reproductive success. The benefit of a long life may differ between the sexes and different mating systems may therefore select for different sex-specific mortality rates. In insects with polyandrous mating systems, females mate throughout their lives and male reproductive success is likely to increase monotonously with lifespan. In monandrous systems, where the mating season is less protracted because receptive females are available only at the beginning of the flight season, male mating success should be less dependent on a long lifespan. Here, we show, in a laboratory experiment without predation, that the duration of the mating season is longer in the polyandrous comma butterfly, Polygonia c-album, than in the monandrous peacock butterfly, Inachis io, and that, in line with predictions, male lifespan is shorter than female lifespan in I. io, whereas male and female lifespans are similar in P. c-album.

Antennal responses to floral scents in the butterflies Inachis io , Aglais urticae (Nymphalidae), and Gonepteryx rhamni (Pieridae)

To better understand the biological role of floral scents for butterflies, electrophysiological responses to floral scents were investigated using combined gas chromatography and electroantennographic detection (GC-EAD). The antennal responses of three butterfly species, Aglais urticae L. (Nymphalidae), Inachis io L. (Nymphalidae), and Gonepteryx rhamni L. (Pieridae) to floral scent compounds from both natural and synthetic mixtures were examined. Floral scents were collected from the butterfly nectar plants Cirsium arvense (L.) (Asteraceae), and Buddleja davidii Franchet cv. (Loganicaeae) with dynamic head-space methods on Tenax-GR and eluted with pentane. These eluates, composed of natural floral scent blends, represent an array of compounds in their natural state. In the GC-EAD analyses eleven compounds were identified from C. arvense with the benzenoid compound phenylacetaldehyde in highest abundance. Seventeen compounds were identified from B. davidii with the irregular terpene oxoisophorone in highest abundance. Thirty-nine synthetic floral scent compounds were mixed in pentane, in equal amounts; about 35 ng were allowed to reach the antennae. The butterflies showed antennal responses to most of the floral scent compounds from both natural and synthetic blends except to the highly volatile monoterpene alkenes. Certain benzenoid compounds such as phenylacetaldehyde, monoterpenes such as linalool, and irregular terpenes such as oxoisophorone, were emitted in relatively large amounts from C. arvense and B. davidii, and elicited the strongest antennal responses. These compounds also elicited strong antennal responses when present in the synthetic scent blends. Thus, the butterflies seem to have many and /or sensitive antennal receptors for these compounds, which points to their biological importance. Moreover, these compounds are exclusively of floral scent origin. For B. davidii, which depends highly on butterflies for pollination, the exclusive floral scent compounds emitted in high abundance could be the result of an adaptive pressure to attract butterflies.

Foraging responses in the butterflies Inachis io , Aglais urticae (Nymphalidae), and Gonepteryx rhamni (Pieridae) to floral scents

For butterflies to be efficient foragers, they need to be able to recognize rewarding flowers. Flower signals such as colours and scents assist this recognition process. For plant species to attract and keep butterflies as pollinators, species-specific floral signals are crucial. The aim of this study is to investigate foraging responses to floral scents in three temperate butterfly species, Inachis io L. (Nymphalidae), Aglais urticae L. (Nymphalidae), and Gonepteryx rhamni L. (Pieridae), in behavioural choice bioassays. The butterflies were allowed to choose bet-ween flower models varying in scent and colour (mauve or green). Flowers or vegetative parts from the plants Centaurea scabiosa L. (Asteraceae), Cirsium arvense (L.) (Asteraceae), Knautia arvensis (L.) (Dipsacaceae), Buddleja davidii Franchet (Loganicaeae), Origanum vulgareL. (Lamiaceae), Achillea millefolium L. (Asteraceae), and Philadelphus coronarius L. (Hydrangiaceae) were used as scent sources. All visits to the models — those that included probing and those that did not — were counted, as was the duration of these behaviours. Both flower-naive and flower-experienced (conditioned to sugar-water rewards, the colour mauve, and specific floral scents) butterflies were tested for their preference for floral versus vegetative scents, and to floral scent versus colour. The butterflies were also tested for their ability to switch floral scent preferences in response to rewards. Flower-naive butterflies demonstrated a preference for the floral scent of the butterfly-favourable plants C. arvense and K. arvensis over the floral scent of the non-favourable plants Achillea millefolium (Asteraceae), and Philadelphus coronarius cv. (Hydrangiaceae). Most of the butterflies that were conditioned to floral scents of either C. arvense, K. arvensis, or B. davidii readily switched theirfloral scent preferences to the one most recently associated with reward, thus demonstrating that floral scent constancy is a result from learning. These findings suggest that these butterflies use floral scent as an important cue signal to initially identify and subsequently recognize and distinguish among rewarding plants.

CanInachis iodetect nectar amino acids at low concentrations?

AbstractThis study testedInachis ioL. butterflies' preference for nectar amino acids using a dilution series (100, 75, 50, 25 and 0%) of the amino acid concentration ofLantana camarato determine how sensitive the insects are to low concentrations of amino acids, such as those found in the flowers of many plant species. Female butterflies clearly detected and preferred nectar amino acids even at the lowest concentration offered, whereas males did not. These results further support the hypothesis that female butterflies detect and select for nectar with amino acids at levels found in the field.

The influence of thermal ecology on the distribution of three nymphalid butterflies

Summary Studies have shown that many adult and immature insects are able to maintain body temperature well above, and often independently of, ambient temperature in the presence of direct solar radiation. They may do so directly by basking, or indirectly via microhabitat choice. The implications for this are often ignored in development models that serve to predict species’ responses to climate change. To investigate the difference in development times attributable to solar input, field development of Aglais urticae, Inachis io and Polygonia c‐album larvae (Lepidoptera: Nymphalidae) was followed both in a natural open situation and in an artificially shaded environment. Each species completed development more quickly in the open, equivalent to a 20%, 10% and 15% reduction in development time, respectively. Observed development times in the artificially shaded environment were used to compare the techniques of rate summation and degree‐day modelling. Rate summation models were found to describe development in the shade best for A. urticae and I. io, although a degree‐day model performed best for P. c‐album, possible reasons for which are discussed. The best‐performing models for each species were modified to include larval thermoregulation data, assuming a linear relationship between body and ambient temperatures during the measured sunshine hours each day, and tested against observed development times in the open situation. Times for 50% adult emergence were predicted exactly for A. urticae, and to an accuracy of 1 day for I. io and 5 days for P. c‐album. The models were tested further using climate data from 128 UK Meteorological Office weather stations across England, Wales and Scotland. Thermoregulation model predictions matched observed UK distribution and voltinism better than predictions made by the standard unmodified models. It was estimated that larval thermoregulation allows A. urticae and I. io populations to persist approximately 200 km further north than would otherwise be possible, and that the extent of bivoltinism may be shifted northwards by around 300 km. These results have significant implications for predicting the effects of global warming on insects’ geographical ranges, the potential distributions of invasive species, and the phenology and voltinism of introduced biocontrol agents as one component of their likely success.

Thermal ecology of gregarious and solitary nettle-feeding nymphalid butterfly larvae.

Group-living in animal populations has many possible ecological and evolutionary explanations, including predator evasion and feeding facilitation. In insects, the thermal balance of solitary and gregarious larvae is likely to differ and may thus have important ecological consequences. The abilities of the larvae of four species of nettle-feeding nymphalid butterflies to thermoregulate were quantified in the field. Larval surface body temperatures of the gregarious Aglais urticae (small tortoiseshell) and Inachis io (peacock) and the solitary Polygonia c-album (comma) and Vanessa atalanta (red admiral) were measured for each instar, in both sunny and overcast conditions, over a seasonal range of temperatures. The results suggested two distinct larval thermal strategies. In the presence of direct sunlight, the exposed gregarious larvae of A. urticae and I. io regulated body temperatures at 32.5 and 31.5°C, respectively, while the temperatures of concealed larvae of P. c-album and V. atalanta were largely dependent on ambient temperatures. In the sun, the range of body temperatures recorded for A. urticae and I. io larvae was fairly narrow relative to ambient temperatures. This suggests a high degree of thermal control in these species. Modal body temperatures coincided with the temperature at which development rate is maximal. Regardless of whether changes in thermoregulation are a cause or consequence of the evolution of gregariousness, the combination of behavioural thermoregulation and gregariousness in larval insects has important implications for voltinism patterns and range extension (via increased development rates). Distributional responses of gregarious and solitary larvae to climatic warming may differ as a result of changes in cloud cover as well as changes in temperature.

Trade-offs between melanization, development time and adult size in Inachis io and Araschnia levana (Lepidoptera: Nymphalidae)?

Effects of melanization in the juvenile stages of the European map butterfly (Araschnia levana) and the peacock butterfly (Inachis io) on the life history traits, larval and pupal development time and size at maturity, and on adult melanization were investigated. Pupae and 5th instar larvae of A. levana vary in degree of melanization, the latter possibly determined by a single major gene. Variation in melanization in I. io occurs only in the pupal stage and is under low genetic control. In both species life history traits and adult melanization are influenced by juvenile melanization, both at phenotypic and genetic levels. Many of the relationships are consistent with trade-offs, e.g. melanized 5th instars of A. levana grow more slowly in early instars and I. io adults from melanized pupae are smaller and less black. However, some results are inconsistent with a trade-off hypothesis. Possible adaptive and physiological explanations are discussed. Araschnia levana shows seasonal polyphenism in wing pattern; pale larvae produced more spring forms, probably resulting from slower growth in the 5th instar. Genetic correlations across environments for larval development time and adult size are to a large extent influenced by larval melanization.

Do Peacock butterflies (Inachis io L.) detect and prefer nectar amino acids and other nitrogenous compounds?

The preferences for nectar amino acids, urea and ammonium ions of peacock butterflies, Inachis io, were tested experimentally. Females clearly preferred a mimic of Lantana camara nectar containing amino acids to an otherwise similar plain sugar solution, whereas males did not discriminate between these test solutions. Neither males nor females discriminated between the full mixture of amino acids in a mimic of L. camara nectar and similar test solutions containing only the single amino acids arginine or proline. Furthermore, the butterflies were not able to detect methionine in the test solutions. Both sexes detected and preferred ammonium ions in test solutions but showed no response to urea. These results support the hypothesis that butterflies can select for high amino acid concentrations in floral nectar. However, it seems unlikely that they select for particular amino acids. The rather unspecific response of I. io males to the nectar constituents tested may result from their relatively low demand for nitrogen for spermatophore and sperm production, while their high activity may make energy supply (i.e. sugar) more important. The preference for ammonium ions suggests that I. io could also acquire nitrogen from ammonium-contaminated soil by puddling, as has been shown for sodium in swallowtail butterflies.

A safety band prevents falling of the suspended pupa of the butterfly Inachis io (Nymphalidae) during moult. A comparison with the girdled pupa of Pieris brassicae (Pieridae, Lepidoptera)

During the pupal moult the suspended prepupa of the butterfly Inachis io completely removes its larval skin (exuvia) from the body. In doing this, the attachment to a silken pad has to be transferred from the anal prolegs of the prepupa to the cremaster of the pupa without losing the hold at any time. Falling is prevented by a short safety band which is drawn off from the innermost layer of the exuvia as it adheres to two prominent, pupal projections when the exuvia is slipped backwards. The projections which lie on the ventral side of the last abdominal segment are covered with numerous, minute spines each orientated in the opposite direction to the removal of the exuvia. The transparent safety band has a gelatinous consistency and is strong enough to withstand the fivefold load of a pupa. By contrast, the prepupa of Pieris brassicae is additionally held in place during moult by a girdle around the back. It usually rests in an upright position. Nevertheless, the pupa also shows the prominent projections covered with spines. The exuvia is held fast by the projections, but only a fold is formed. The formation of a safety band is never observed. The connection of the exuvia to the projections is sufficient to hold the tip of the abdomen within reach of the pad for hooking the cremaster therein. However, the pupae of those species in Satyrinae which pupate lying in cocoons or cells lack any kind of projections as well as spines.