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How do sensory receptors in an insect’s body wall help start molting?

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Illustration showing a variety of adult insects, each labeled with its common name and order, including walkingstick, earwig, stonefly, tree cricket, dragonfly, female scale, cat flea, thrips, sucking louse, thysanuran, ant, scarab beetle, stinkbug, mosquito, and cabbage butterfly, highlighting their diverse shapes and sizes. — insect An illustration of insect diversity.

In insects, sensory receptors located in the body wall play a critical role in initiating the molting process. These receptors detect when the insect's internal soft tissues have grown to the point that they have filled the existing exoskeleton.1

Once these receptors sense that the body has become sufficiently distended, they trigger the production of a hormone from neurosecretory cells within the brain. This signal initiates a hormonal cascade, stimulating the prothoracic gland to secrete ecdysone, the molting hormone that ultimately directs the epidermis to begin forming a new cuticle.21