Burrowing Mayflies

Family Ephemeridae

Identification: Most have clear wings; a few have spotted wings. Base of M2 in FW extends toward Cuh then bends abruptly distad. R4+5 in HW not forked. Hind tarsi 4-segmented.

Nymphs occur in ponds, lakes, and large rivers, and are usually burrowing in habit. This group includes our largest mayflies. Some often emerge from lakes and rivers in enormous numbers.

STREAM MAYFLIES Family Heptageniidae Identification: Base of M2 in FW nearly straight. Cubital intercalarles in FW in 2 parallel pairs. R4+5 in HW forked. Hind tarsi 5-segmented.

Nymphs are flattened and streamlined, and occur on the underside of stones in streams. Adults are medium-sized to small, and usually clear-winged.

SMALL MAYFLIES Family Baetidae Identification: M2 in FW as in Heptageniidae. Cubital intercalarles in FW variable, but not in 2 parallel pairs. R4+5 in HW variable. Venation in HW often reduced (HW sometimes lacking). Hind tarsi 3- or 4-segmented.

Nymphs are more cylindrical than those of Heptageniidae, and occur in various aquatic habitats. Adults vary in size and appearance but are usually less than 15 mm.

Dragonflies and Damselflies: Order Odonata

Identification: Two pairs of elongate, membranous, many-veined wings. Wings at rest usually held outstretched (Anisoptera) or together above body (Zygoptera). FW and HW similar in size and shape (Zygoptera), or HW broader at base than FW (Anisoptera). Abdomen long and slender. Compound eyes large, often occupying most of head. Antennae very shorty bristlelike, and inconspicuous. Prothorax small, the other 2 thoracic segments making up most of thorax. Tarsi 3-segmented. Copulatory organs of cf located on ventral side of 2nd abdominal segment. Cerci present, 1-segmented, in male functioning as clasping organs during mating. Mouth parts chewing. Metamorphosis simple.

Similar orders: (1) Neuroptera (p. 140): antennae long; tarsi 5-segmented; wing venation different. (2) Hymenoptera (p. 312): antennae long; tarsi 5-segmented; HW smaller than FW; wings with fewer veins. (3) Diptera (p. 260): 1 pair of wings. (4) Ephem-eroptera (p. 65): 2-3 long tails; HW smaller than FW; very soft-bodied.

Immature stages: Nymphs are aquatic, and occur in ponds and streams. They feed on other insects, which are captured with a peculiarly modified labium. When not in use, the labium is folded under the head, and when used is thrust forward very quickly to catch prey in a pair of clawlike structures at its apex. Labium when extended is sometimes as long as }/& body length. Gills of the nymph are located in rectum (Anisoptera) or are in form of 3 leaflike tails (Zygoptera).

Habits: Adults usually found near water (in which nymphs live), but many are strong fliers and can range many miles. Often fly in tandem, the male holding female by back of head or the prothorax with the appendages at end of his abdomen. Eggs generally laid in aquatic vegetation or are washed off end of the abdomen when female flies low over water. Adults relatively large insects (about 1-33^ in.), and many are brightly colored. Most are good fliers, and spend a large part of their time on the wing. They feed on other insects they catch on the wing.

Importance: All stages are predaceous, feeding on mosquitoes, midges, and other small insects, and help keep them under control. Adults attempt to bite when handled, but only the larger dragon-flies can inflict a painful pinch; they do not sting. Classification: Two suborders, Anisoptera and Zygoptera, which differ in wing shape, position of wings at rest, appendages at end of abdomen, and characters of nymphs. Principal characters separating families are those of wing venation. No. of species: World, 4950; N. America, 400.

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