Caterpillars (lepidopteran larvae) are likely attacked by various types of predators. Therefore, caterpillars defend themselves against predators in various ways. We have been studying anti-predator defense in caterpillars.

Climbing behavior

   Caterpillars are major herbivores in forest canopies.  When caterpillars involuntarily or intentionally drop from the tree canopy, they can regain their original position by climbing silk lifelines spun out from the head spinnerets. On the basis of our observations, we proposed a hypothesis regarding the evolution of lifeline climbing behavior in Lepidoptera.

Hairs as anti-predator defences

   Some caterpillar species have long and dense hairs. To clarify how hairs can protect caterpillars from predators’ weapons, we observed carabid beetles (Calosoma maximowiczi) attacking both smooth and hairy caterpillar species under laboratory conditions. 

   A long-haired species Lemyra imparilis was able to escape from carabid attacks. Dorsal hairs of L. imparilis larvae were much longer than the mandible length of carabid adults. Furthermore, we cut the dorsal hairs of L. imparilis larvae shorter than the carabids’ mandibles. Cutting the dorsal hairs of L. imparilis larvae resulted in fewer carabid attacks with higher success rates. Therefore, long hairs can protect L. imparilis larvae from carabid mandibles.

Sound production

   Some caterpillar species produce sounds. Larvae of Langia zenzeroides (Lepidoptera: Sphingidae) produce sounds when attacked. When a larva was submerged in water, it produced air bubbles from a pair of spiracles on the eighth abdominal segment. Therefore, L. zenzeroides larvae produce sounds by forcing air through the eighth pair of abdominal spiracles. Similarly, larvae of Rhodinia fugax (Lepidoptera: Saturniidae) produce sounds by forcing air through the first abdominal spiracles.

Publication

Sugiura, S., Takanashi, T., Kojima, W. & Kajiura, Z. (2020) Squeaking caterpillars: independent evolution of sonic defense in wild silkmoths. Ecology, 101(10): e03112.

Sugiura, S. & Takanashi, T. (2018) Hornworm counterattacks: Defensive strikes and sound production in response to invertebrate attackers. Biological Journal of the Linnean Society, 123: 496–505. [Highlighted in: Malhotra, R. (2018) Watch this caterpillar fling its beetle attacker through the air. Science]

Sugiura, S. & Yamazaki, K. (2017) Scavenging behavior in leaf-feeding caterpillars. Journal of the Lepidopterists’ Society, 71(1): 59–61.

Sugiura S (2016) Bagworm bags as portable armour against invertebrate predators. PeerJ, 4: e1686.

Kageyama, A. & Sugiura, S. (2016) Caterpillar hairs as an anti-parasitoid defence. The Science of Nature – Naturwissenschaften, 103:86.

Sugiura S (2016) Bagworm bags as portable armour against invertebrate predators. PeerJ, 4: e1686.

Sugiura, S. & Yamazaki, K. (2014) Caterpillar hair as a physical barrier against invertebrate predators. Behavioral Ecology, 25:975–983. [Highlighted in: Law, Y.-H. (2014) For some caterpillars, a hairy back can save your life. Earth Touch News]

Sugiura, S. & Yamazaki, K. (2006) The role of silk threads as a lifeline in caterpillars: pattern and significance of lifeline climbing behaviour. Ecological Entomology, 31 (1): 52-57.  [Highlighted in: Dahlem, G. A. ed. (2007) Rope-climbing techniques in caterpillars. American Entomologist 53 (2): 114-115]