Hearing in Caterpillars of the Monarch Butterfly (<i>Danaus plexippus</i>)
Bibliographic record
Abstract
Many species of caterpillars have been reported to respond to sound, but there has been limited formal study of what sounds they hear, how they hear them, and how they respond to them. Here we report on hearing in caterpillars of the Monarch butterfly (Danaus plexippus). Fourth and fifth instar caterpillars respond to sounds by freezing, contracting, and flicking their thorax in a vertical direction. Behavioural responses were evoked by sound frequencies between 50 and 900 Hz, with best sensitivity at 100-200 Hz. The lowest mean threshold was 79 dBSPL (particle velocity 605 µm/s) at 150 Hz. When presented with a repeated 200 Hz sound tone, caterpillars habituate by no longer responding. A series of ablation experiments confirmed that the primary sensory receptors are a pair of long hairs, called trichoid sensilla, located on the upper prothorax. These sensilla are ∼450 µm long, rest in a socket, and are innervated by a single bipolar sensory neuron. Removal of these setae reduced responses significantly compared to controls. Other setae contributed minimally to hearing in response to 200 Hz tones, and tubercles and prothoracic shields played no apparent role in sound reception. We propose that hearing functions to prevent attacks by aerial insect predators and parasitoids, which produce flight sounds in the frequency range of the caterpillars’ sensitivity. This research lays the foundation for further investigations on the function and evolution of hearing in caterpillars, and has significance for conservation of threatened monarch butterfly larvae living near noisy urban environments and roadways.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".