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ADEPHAGA

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Originally appearing in Volume V06, Page 671 of the 1911 Encyclopedia Britannica.
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ADEPHAGA .—This tribe includes beetles of carnivorous See also:

habit with five segments on every See also:foot, See also:simple See also:thread-like feelers with none of the segments enlarged to See also:form See also:club or pectination, and the See also:outer lobs (galea) of the first maxilla usually two-segmented and palpiform (fig. 4 b). The transverse See also:fold of the See also:hind-wing is towards the tip, about two-thirds of the wing-length from the See also:base. At this fold the median nervure stops and is joined by a See also:cross nervure to the radial, which can be distinguished throughout its length from the subcostal. There are four malpighian tubules. In the ovarian tubes of Adephaga small yolk-See also:chambers alternate with the See also:egg-chambers, while in all other beetles there is only a single large yolk-chamber at the narrow end of the See also:tube. The larvae (fig. 2 c) are active, with well-chitinized cuticle, often with elongate tail-feelers (cerci), and with five-segmented legs, the foot-segment carrying two claws. The generalized arrangement of the wing-nervure and the nature of the larva, which is less unlike the adult than in other beetles, distinguish this tribe as See also:primitive, although the perfect See also:insects are, in the r See also:lore dominant families, distinctly specialized. Two very small families of aquatic beetles seem to stand at the base of the See also:series, the Amphizoidae, whose larvae. are broad and well armoured with See also:short cerci, and the Pelobiidae, which have elongate larvae, tapering to the tail end, where are See also:long paired cerci and a median See also:process, recalling the See also:grub of a Mayfly. The Dyticidae (fig. 2) are Adephaga highly specialized for See also:life in the See also:water, the hind-legs having the segments short, broad and fringed, so as to be well adapted for See also:swimming, and the feet without claws.

The metasternum is without the transverse linear impression that is found in most families of Adephaga. The beetles are ovoid in shape, with smooth contours, and the elytra See also:

fit over the edges of the See also:abdomen so as to enclose a See also:supply of See also:air, available for use when the See also:insect remains under water. The fore-legs of many male dyticids have the three proximal foot-segments broad and saucer-shaped, andcovered with suckers, by means of which they secure a See also:firm hold of their mates. Larval dyticids (fig. 2 b) possess slender, curved, hollow mandibles, which are perforated at the tip and at the base, being thus adapted for sucking the juices of victims. Large dyticid larvae often attack small fishes and tadpoles. They breathe by piercing the See also:surface film with the tail, where a pair of spiracles are situated. The pupal See also:stage is passed in an earthen See also:cell, just beneath the surface of the ground. Nearly 2000 See also:species of Dyticidae are known: they are universally distributed, but are most abundant in cool countries. The Haliplidae form a small aquatic See also:family allied to the Dyticidae. The. Carabidae, or ground-beetles, comprising 13,000 species, form FIG. y.—Cicindela sylvatica FIG.

8.—Manticora tuberculata. (See also:

Wood See also:Tiger-See also:Beetle). See also:Europe. S. See also:Africa. the largest and most typical family of the Adephaga (See also:figs. 4, 5, 6), the legs of all three pairs being alike and adapted for rapid See also:running. In many Carabidae the hind-wings are reduced or absent, and the elytra fused together along the suture. Many of our native species spend the See also:day lurking beneath stones, and sally forth at See also:night in pursuit of their See also:prey, which consists of small insects, earthworms and snails. But a number of the more brightly coloured ground-beetles run actively in the See also:sunshine. The carabid larva is an active well-armoured grub with the legs and cerci variable in length. See also:Great See also:differences in the See also:general form of the See also:body may be observed in the family.

Phoenix-squares

For example, the stout, heavy body of Carabus (fig. 6) contrasts markedly with the wonderful flattened abdomen and elytra of Mormolyce (fig. 4), a Malayan genus found beneath fallen trees, a situation for which its compressed shape is admirably adapted. See also:

Blind Carabidae form a large proportion of See also:cave- dwelling beetles, and several species of great See also:interest live between See also:tide-marks along the seashore. The Cicindelidae, or tiger-beetles (figs. 7, 8) are the most highly organized of all the Adephaga. The inner See also:lobe (lacinia) of the first maxilla terminates in an articulated See also:hook, while in the second maxillae (labium) both inner and outer lobes (" ligula " and " See also:para-glossae ") are much reduced. The See also:face (clypeus) is broad, extending on either See also:side in front of the insertion of the feelers. The beetles are elegant insects with long, slender legs, running quickly, and flying in the sunshine. The pronotum and elytra are often adorned with See also:bright See also:colours or metallic lustre, and marked with stripes or spots. The beetles are fierce in nature and predaceous in habit, their See also:sharp toothed mandibles being well adapted . for the See also:capture of small insect-victims.

The larvae are more specialized than those of other Adephaga, the See also:

head and prothorax being very large and broad, the succeeding segments slender and in-completely chitinized. The fifth abdominal segment has a pair of strong dorsal hook-like processes, by means of which the larva supports itself in the burrow which it excavates in the See also:earth, the great head blocking the entrance with the mandibles ready to seize on any unwary insect that may venture within reach. Two or three families may be regarded as aberrant Adephaga. Gyrinus sulcatus (Grooved Whirligig). Europe. Antenna of Larva of Gyrinus. Gyrinus. The Paussidae are a very remarkable family of small beetles, mostly tropical, found only in ants' nests, or flying by night, and apparently migrating from one See also:nest to another. The number of antennal segments varies from eleven to two. It is supposed that these beetles secrete a sweet substance on which the ants feed, but they have been seen to devour the ants' eggs and grubs. The Gyrinidae, or whirligig beetles (fig. 9), are a curious aquatic family with the feelers (fig.

9, b) short and redu"ed as in most Paussidae. They are flattened See also:

oval in form, circling with gliding See also:motion over the surface film of the water, and occasionally diving, when they carry down with them a bubble of air. The fore-legs are elongate and adapted for clasping, while the short and flattened intermediate and hind legs form very perfect See also:oar-like propellers. The larva of Gyrinus (fig. 9, c) is slender with elongate legs, and the abdominal segments carry paired tracheal gills.

End of Article: ADEPHAGA

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