Belly foot

Swallowtail caterpillar ( Papilio machaon ). The first three pairs of sternum bones in the front (right), the four pairs of ventral feet in the middle (three of which are shown enlarged) and the bulging pusher at the end of the abdomen are clearly visible .

Abdominal feet , anal feet, or abdominal feet or (not entirely correct) legs are fleshy, stubby and undivided extremities in different insect larvae that are arranged in pairs . They are used for locomotion and occur in some larvae of plant wasps (Symphyta) and flies (Brachycera) and in particular in almost all caterpillars . However, these are not real legs, only skin protuberances, as they are unsegmented. For this reason, the term legs is actually incorrect and should not be used. They have their own muscles for movement , but they are not well developed. The abdominal feet of the last abdominal segment are also referred to as pushers due to their function .

In some, especially mining caterpillars, the ventral feet have hook wreaths (wreath feet, pedes coronati), in free-living caterpillars these are covered with chitin claws for better clinging (clamp feet, pedes semicoronati). They are much more domed in shape than the real legs and are usually widened like a suction cup at the end. The animals usually have four pairs of ventral feet, which are usually located on the 6th to 9th segment, and another pair, the so-called followers, on the 13th segment (10th abdominal segment).

In almost all caterpillars, there are two footless segments between the first three pairs of legs that attach to the breast segments ( sternites ) and the first segment with ventral feet. Only the primeval moths (Micropterigidae) also have these belly feet. Some butterfly families differ from this physique. Spanners (Geometridae) are missing the first three pairs, some owl butterflies (Noctuidae) are missing the first or the first two pairs. In the case of the snail spiders (Limacodidae), in addition to the real pairs of legs, the pectoral feet have receded into tiny stumps. Similar to slugs , they can only move about by crawling. In the larvae of the plant wasps, the gap between the sternum and the first pair of ventral feet consists of only one segment, which means that they can be distinguished from most caterpillars.

Number of abdominal bones in insect larvae on abdominal segments A1 – A9 / 10 (T1–3: thorax segments with 6 sternum bones)

Larvae of	Name of the larvae	Group / family	order	A1	A2	A3	A4	A5	A6	A7	A8	A9 / 10 (follower)	Total feet with T1–3
Butterflies	Caterpillars	lots	Lepidoptera	-	-	2	2	2	2	-	-	2	16
Primeval moths	Caterpillars	Micropterygidae	Lepidoptera	2	2	2	2	2	2	2	2	2	24
Owl butterflies	Caterpillars	Noctuidae (some)	Lepidoptera	-	-	-	2	2	2	-	-	2	14th
Owl butterflies	Caterpillars	Noctuidae (some)	Lepidoptera	-	-	-	-	2	2	-	-	2	12
Stretcher	Caterpillars	Geometridae	Lepidoptera	-	-	-	-	-	2	-	-	2	10
Plant wasps	Anal caterpillars	Symphyta (many)	Hymenoptera	-	2	2	2	2	2	2	2	2	22nd
Plant wasps	Anal caterpillars	Symphyta (some)	Hymenoptera	-	2	2	2	2	2	2	-	2	20th
Plant wasps	Anal caterpillars	Symphyta (some)	Hymenoptera	-	2	2	2	2	2	-	-	2	18th
Sawfly wasps	Anal caterpillars	Pamphilinae	Hymenoptera	-	-	-	-	-	-	-	-	2	8th
Beak flies	Larvae	all	Mecoptera	2	2	2	2	2	2	2	2	2	24
Caddis flies	Larvae	all	Trichoptera	-	-	-	-	-	-	-	-	2	8th

literature

• Pusher. and anal foot. In: Herder-Lexikon der Biologie. Spektrum Akademischer Verlag, Heidelberg 2003, ISBN 3-8274-0354-5 .

Individual evidence

1. ^ Stefan von Kéler : Entomological dictionary. Akademie-Verlag Berlin 1963. page 80.