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Caterpillars (Lepidoptera and Symphyta larvae) employ diverse visual defensive tactics, and effectiveness of such tactics may be highly dynamic across time due to seasonal changes in the predator assemblages and their preferences. However, this has rarely been studied especially in tropical regions. Here we assessed temporal changes in the defensive value of caterpillar color and shape, using six types of plasticine dummy caterpillars: three colors (green, black, and white) × two shapes (curled and straight). These dummy caterpillars were deployed five times over different seasons in tropical forests of Xishuangbanna (China) and, as a comparison, twice in a temperate forest of Hirosaki (Japan). The colors and shapes of dummy caterpillars simulate visual traits of black sawfly larvae which take the curled resting posture in tropical rainforests of Xishuangbanna, apparently masquerading excrements commonly found on plants, while in Hirosaki there is no black‐curled sawfly larvae and few excrements on plants. We found no significant effects of caterpillar colors or shapes on predation in Hirosaki. In contrast, black and curled caterpillars received significantly lower predation by birds in Xishuangbanna constantly across time. However, we were unable to provide evidence that the black‐curled sawfly larvae are masquerading as excrements. Shapes of the dummy caterpillars also affected the predation by ants and parasitoid wasps at certain times. This is the first report on ecological function of the curled posture of sawfly larvae, and we demonstrated the importance to assess the temporal dynamics of predation and effectiveness of defensive tactics in tropical forests.

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Almost all snakes swallow their prey whole. However, a few species are known as exceptions. Two species of Asian crab‐eating snakes tear off crab legs and ingest them one at a time to eat prey that is otherwise too large. Two species of leptotyphlopid blindsnakes break off the head of termites or suck abdominal contents of termites, discarding remains of termites. Here, we show that a typhlopid blindsnake Indotyphlops braminus decapitates its termite prey and consumes only the thorax and abdomen. In our feeding trials, I. braminus decapitated a median of 47% of termites they eat, while swallowing the remaining termites whole. Decapitation did not affect ingestion speed, and therefore, it is unlikely that decapitation assists for fast ingestion. Ingested termite heads often remain undigested in the feces, implying that the decapitation functions to remove an indigestible part of termites. Decapitation might also be related to circumvention of chemical defenses of termites because termite heads often contain toxic compounds. These observations showed unusual feeding behavior used by a basal snake, which could be associated with removal of indigestible and/or toxic parts of prey items.

Ants often tend and protect the larvae of various myrmecophilous lycaenid species, which influences the fitness of butterflies by altering their growth and developmental time. Tending produces diverse effects depending on lycaenid sex and the lycaenid/ant species combination. Effects are widely variable, especially in facultatively myrmecophilous lycaenids such as Plebejus argyrognomon praeterinsularis, because they are associated with several ant species and can survive without any ant tending. We studied the effects of ant tending on the adult body mass and larval developmental time of P. argyrognomon praeterinsularis. Female larvae grew significantly heavier as adults when tended by Camponotus japonicus rather than by either Lasius japonicus or no ant species. Ant tending did not affect the body mass of adult males or the developmental time of either male or female larvae. Thus, tending by C. japonicus could increase the fitness of P. argyrognomon praeterinsularis by increasing the mass of females without prolonging the duration of vulnerable immature stages, because larger females generally lay more eggs. This means that even facultatively myrmecophilous lycaenids might gain fitness benefits from particular ant species, which could be important in the conservation and management of at-risk species of facultatively myrmecophilous lycaenids.

Eusocial insects can express surprisingly complex cooperative defence of the colony. Brood and reproductive castes typically remain in the nest and are protected by workers' various antipredator tactics against intruders. In Madagascar, a myrmicine ant, Aphaenogaster swammerdami , occurs sympatrically with a large blindsnake, Madatyphlops decorsei . As blindsnakes generally specialize on feeding on termites and ants brood by intruding into the nest, these snakes are presumably a serious predator on the ant. Conversely, a lamprophiid snake, Madagascarophis colubrinus , is considered to occur often in active A . swammerdami nests without being attacked. By presenting M . colubrinus , M . decorsei and a control snake, Thamnosophis lateralis , at the entrance of the nest, we observed two highly specialized interactions between ants and snakes: the acceptance of M . colubrinus into the nest and the cooperative evacuation of the brood from the nest for protection against the ant-eating M . decorsei . Given that M . colubrinus is one of the few known predators of blindsnakes in this area, A . swammerdami may protect their colonies against this blindsnake by two antipredator tactics, symbiosis with M . colubrinus and evacuation in response to intrusion by blindsnakes. These findings demonstrate that specialized predators can drive evolution of complex cooperative defence in eusocial species.

Coccinellid pupae have various defensive traits, such as keeping their final‐instar larval exuviae and secreting droplets containing defensive chemicals at the tips of glandular hairs. Although each of these traits has been described separately in different species, it is unclear how each defensive trait functions when more than one trait coexists. We found that pupae of the ladybird Scymnus posticalis have two different types of traits; they were partially covered with their own final‐instar larval exuviae, with thick wax structures, and had many glandular hairs secreting transparent droplets on the exposed parts of the body without waxy exuviae (head and medial parts of thoracic and abdominal dorsum). In this study, the defensive effects of these two traits were evaluated against two ant species, Tetramorium tsushimae and Lasius japonicus, which are potential predators. When encountering a pupa, neither ant species were able to make frequent physical contact with the exposed parts of the pupa because of the presence of the waxy exuviae. When touching the exposed body part that was covered with droplets, both ant species immediately stepped backward and then swept their antennae. The droplets suppressed ant feeding when mixed with sucrose solution, suggesting that the droplets contain repellent chemicals. These results indicate that the two traits of S. posticalis pupae (the larval waxy exuviae and the droplets) effectively play defensive roles against ants, functioning as a physical obstruction and a chemical repellent, respectively.

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