Proleg

Caterpillar-description

Chenille de Grand porte queue (macaon) Fausses pattes

Craesus septentrionalis

Proleg

File:Proleg.jpg

Prolegs of a caterpillar

Prolegs are stubby, fleshy, and non-segmented appendages found on the larvae of certain insects, particularly the Lepidoptera (caterpillars) and some Hymenoptera (sawflies). These structures are not true legs but serve a similar function in locomotion and stability.

Structure and Function

Prolegs are typically equipped with tiny hooks called crochets that help the larva grip onto surfaces. These hooks are arranged in various patterns, which can be used to identify different species of caterpillars. The number and arrangement of prolegs can vary among species, but they are usually found on the abdominal segments of the larva.

Distribution

In Lepidoptera, prolegs are usually found on the third to sixth abdominal segments and the last segment. In contrast, sawfly larvae, which belong to the order Hymenoptera, have prolegs on every abdominal segment except the last one.

Development

Prolegs are a temporary feature of the larval stage and are lost during metamorphosis when the insect transitions to its adult form. During this process, the larva undergoes significant morphological changes, and the prolegs are reabsorbed or transformed.

Comparison with True Legs

True legs, or thoracic legs, are jointed and segmented, found on the thoracic segments of the insect. In contrast, prolegs are unsegmented and lack the jointed structure of true legs. Despite these differences, both types of legs serve the purpose of aiding in movement and stability.

Significance in Identification

The presence, number, and arrangement of prolegs are important characteristics used in the identification and classification of caterpillars and sawfly larvae. Entomologists often rely on these features to distinguish between species and to understand their evolutionary relationships.

Related Pages

• Lepidoptera
• Hymenoptera
• Caterpillar
• Metamorphosis
• Insect anatomy