Identifying Aquatic Insects From Your Pond

Transcription

1 Identifying Aquatic Insects From Your Pond Penobscot County Soil & Water Conservation District Natural Resources Conservation Service 28 Gilman Plaza, Suite #2 Bangor, ME Tel: (207) Fax: (207)

2 Identifying Aquatic Insects From Your Pond The following aquatic insects include some of those that you might encounter when exploring your pond. This guide is intended to help you identify these insects and to learn some interesting characteristics about each. Mayfly (Order: Ephemeroptera) Habitat of Nymph: Fresh running water of ponds and streams. Habitat of Adult: Short lived flying insect that mates and then dies. Distinguished from other nymphs by seven pairs of gills along the abdomen. Oxygen is absorbed from water. Nymphs generally have three tails attached to the end of the abdomen. Wing pads are visible on the nymph. Nymphs feed on live and decaying vegetation. Nymphs are a common food source for trout and other fish. Mayfly nymphs require 4 to 10 ppm of dissolved oxygen for survival. Nymphs are up to 2.5 cm long. They have three pairs of segmented legs with one claw at the end of each leg. Dragonfly (Order: Odonata) Habitat of Nymph: Ponds marshes and slow moving streams. Habitat of Adult: Fast flying insect. Distinguished by large compound eyes with nearly 360-degree vision in both the nymph and adult stage. Nymphs have "lips" hinged in two places with grasping pincers on the end for catching prey. Brown and green bodies tend to provide camouflage and allow the nymph to blend in with the aquatic habitat of plants and pond bottoms. Gills inside the abdomen obtain oxygen. Water drawn into the abdomen and through the gills is expelled to propel the nymph through the water. Dragonfly nymphs require 4 to 8 ppm of dissolved oxygen for survival. They have three pairs of segmented legs on upper part (thorax) of body. Dragonfly larvae can be distinguished from damselfly larvae by a wide to oval abdomen that may end in wedge shaped extensions. Nymphs are predators and feed on mollusks, other insects, crustaceans, worms, and small fish. Nymphs are a food source for some fish.

3 Damselfly (Order: Odonata; Suborder: Zygoptera) Habitat of Nymph: Ponds, marshes, and slow moving streams. Habitat of Adult: Fast flying insect. In the same order as dragonflies and similar to dragonflies but generally smaller and more delicate. Distinguished by large compound eyes with nearly 360-degree vision in both the nymph and adult stage. Nymphs have "lips" hinged in two places with grasping pincers on the end for catching prey. Brown and green bodies tend to provide camouflage and allow the nymph to blend in with the aquatic habitat of plants and pond bottoms. Three leaf-like gills at the base of the abdomen obtain oxygen. Damselfly nymphs require 4 to 8 ppm of dissolved oxygen for survival. Damselfly nymphs can be distinguished from dragonfly nymphs by a narrow body with three gills extending in a tripod formation at the end of body. The three pairs of legs are long and spindly. Nymphs are predators and feed on mollusks, other insects, crustaceans, worms, and small fish. Nymphs are a food source for some fish. Stonefly (Order: Plecoptera) Habitat of Nymph: Cold lakes or fast moving streams. Habitat of Adult: Flying insect.

4 Distinguished by obvious wing pads on nymph and two tails that remain on the adult. They also do not have leaf like gills along both sides of the abdomen as the mayfly does. Oxygen is obtained by single gills under the legs or through the skin surface. Stonefly nymphs require 8 to 10 ppm of dissolved oxygen for survival. They have two long antennae much longer than the head. They have three pairs of segmented legs that end in small hooks. The nymph appears to be flattened in shape for crawling along and under stones. Nymphs feed on decaying plants and animals or other small macroinvertebrates. Nymphs are a food source for some fish. Water Strider (Order: Hemiptera) Habitat of Nymph: Ponds and slow moving streams. Habitat of Adult: Ponds and slow moving streams. Water striders appear to skate across the water surface. Their legs can pick up vibrations of other organisms. Oxygen is absorbed by spiracles or specialized holes in their skin surface.

5 Giant Water Bug (Order: Hemiptera; Family: Belostomatidae) Habitat of Nymph: Ponds and slow moving streams. Habitat of Adult: Ponds and slow moving streams. The Giant Water Bug gets oxygen through a snorkel like breathing tube that extends to the water surface. They have three pairs of jointed legs. The front pair has a modified hook for catching and holding prey. Giant Water Bugs may be up to 8 cm in size. True predators in the aquatic environment, Giant Water Bugs will attack prey that are 20 times larger in size. Water Scorpion (Order: Hemiptera; Family: Nepidae) Habitat of Nymph: Ponds and slow moving streams. Habitat of Adult: Ponds and slow moving streams. Water Scorpions get oxygen through long breathing tubes at the base of the abdomen. They look more like sticks than like insects. They are up to 10 cm in length. They have three pairs of jointed legs. The front pair has a set of single hooks for capturing and holding prey. Water Boatman (Order: Hemiptera) Habitat of Nymph: Ponds, running water of streams and intertidal marshes. Habitat of Adult: Ponds, running water of streams and intertidal marshes.

6 Water Boatmen have middle and hind legs covered with long swimming hairs. They eat decaying matter as well as other animals. Because they rely on atmospheric oxygen many species are tolerant of pollution and can live in oxygen-poor environments. Atmospheric oxygen is trapped as an air bubble (or plastron) beneath microscopic hairs. Backswimmer (Order: Hemiptera) Habitat of Nymph: Ponds, running water of streams and intertidal marshes. Habitat of Adult: Ponds, running water of streams and intertidal marshes. Backswimmers have middle and hind legs covered with long swimming hairs like water boatman but swim on their back. Mosquito (Order: Diptera) Habitat of Larvae: Generally ponds, marshes, lakes and slow moving steams some species have adapted to fast moving streams. Habitat of Adult: Small flying insect. Larvae have a small siphon or snorkel tube to acquire oxygen from the air. They can tolerate waters with very low levels of dissolved oxygen. Mosquito larvae can tolerate levels of dissolved oxygen of less than 4 ppm. Larvae are a food source for fish.

7 Cranefly (Order: Diptera; Family: Tipulidae) Habitat of Larvae: Ponds, lakes, and marshes. Habitat of Adult: Flying insect. Larvae are plump, long, and cylindrical. Larvae may be up to 10 cm in length. At the end of the abdomen are spiracles or breathing holes that look like fingers. The larvae will move to the water surface to breathe oxygen from the air. The abdomen of some species is flattened. The back end usually has several small extensions or lobes. Often the small head is not visible and is hidden within the first segment of the body. Larvae are a food source for fish. Midges (Order: Diptera; Family: Chironomidae) Habitat of Larvae: Bottom sediments of lakes, ponds, or streams. Habitat of Adult: Small flying insect. Larvae are up to 1.5 cm in length. Larvae bodies are usually thin, slightly curved, and segmented. They have one pair of tiny fleshy prolegs below the head and one pair at the back end. The end sometimes has tiny tufts or extensions. They feed on smaller larvae, decaying matter, and microorganisms. They are an important component of the aquatic food web. Larvae are a food source for fish. Typically, midge larvae live in the bottom sediments of lakes and streams. Their remains form an organic ooze.

8 Two main groups of midges are distinguished by their method of obtaining and storing oxygen. Midges that are red in color are termed blood midges. They can store oxygen in their body fluid with a compound similar to hemoglobin. This provides the distinguishing red color for blood midges. Blood midges can tolerate very low levels of dissolved oxygen. Other midges obtain oxygen from the air with breathing tubes. Both blood midges and other midges are distinguished from other aquatic fly larvae by a thin uniformly wide segmented body. Midges can tolerate levels of dissolved oxygen of less than 4 ppm. Caddisfly (Order: Trichoptera) Habitat of Larvae: Streams and ponds Habitat of Adult: Land dwelling flies. Many caddisfly larvae can be recognized by soft bodies which are covered by tube like cases that the larvae build from twigs, leaves, grasses, pebbles and sand grains. Some larvae do not build cases where the current is not strong such as ponds. Larvae maybe up to 4 cm in length. They have three pairs of segmented legs on the upper - middle part of the body and two small fleshy extensions at the end of the abdomen that end in a small hook. Filamentous gills may be present on the underside or the end of the abdomen. They have a characteristic motion know as the "Caddisfly Dance" of wiggling back and forth and up and down. Different species have different feeding habits. Some live on dead leaves and decaying matter, others feed on plants, and some prey on other organisms. Oxygen is absorbed through the body surface. Larvae and the pupae are common food sources for trout and other fish.

9 Maggots (Rat-tailed Maggot) (Order: Diptera) Habitat of Larvae: Streams and ponds Habitat of Adult: Land dwelling flies. Larvae have a long snorkel-like tail that draws in oxygen from the atmosphere. The body is cylindrical. Tolerates low oxygen levels. It is a scavenger and feeds off dead decaying matter. Predaceous Diving Beetle (Order: Coleoptera; Family: Dytiscidae) Habitat of Larvae: Slow moving waters. Habitat of Adult: Slow moving waters. Larvae have six jointed legs. The body is segmented with a narrow collar behind the head. Abdomen may have filaments but not hooks. The head has large crescent shaped mandibles or mouthparts.

10 * Most of the information contained within this guide is from a web page by David T. Hansen for the Water Quality Event of Science Olympiad. Illustrations are from Edelstein and information source is Kellogg. Kellogg Monitor's Guide to Aquatic Macroinvertebrates by Loren and Larkin Kellogg, Save Our Streams Series, Izaak Walton League of America; 707 Conservation Lane, Gaithersburg MD , Edelstein Pond and Stream Safari, A Guide to the Ecology of Aquatic Invertebrates by Karen Edelstein, Cornell University Cooperative Extension; 4-H Leader Guide 147L24; Ithaca New York; June, The U.S. Department of Agriculture (USDA) and the Penobscot County SWCD prohibit discrimination in all their programs and activities on the basis of race, color, national origin, gender, religion, age, disability, political beliefs, sexual orientation, or marital or family status. (Not all prohibited bases apply to all programs.) Persons with disabilities who require alternative means for communication of program information (Braille, large print, audiotape, etc.) should contact USDA s TARGET Center at (202) (voice and TDD). To file a complaint of discrimination, write USDA, Director, Office of Civil Rights, Room 326-W, Whitten Building, 1400 & Independence Avenue, S.W., Washington D.C or call (202) (voice and TDD). USDA and PCSWCD are equal opportunity providers and employers.

11 DRAGONFLY LARVAE Petaltails (Petaluridae) Petaltail larvae are generally short with thick hairy 7-segmented antennae that are shorter than the head. The labium is flat; the palps are broadened partially covering the face. The palpal lobes have a large spur at the base of the moveable hook; their legs appear twisted. These larvae are semi-aquatic, sedentary and mostly nocturnal. They wait in the muck in seepage waters for prey to come their way. Darner (Aeshna) These larvae are generally smooth, slender and very long. The head appears flattened with 5-7 slender bristle-like antennae which are similar and size and shape. These particular larvae have well developed eyes that are positioned laterally on the head. The labium is very long and flat when viewed laterally and is held under the head not in front of the face like in our larvae. The prementum and palpal lobes are flattened. The thorax is slightly depressed while the abdomen is slightly widened from the base to beyond the middle, than narrowed at the end. Some species may even present with sharp lateral spines on segments 5-9. Legs are long and thin. These larvae are mostly brown in coloration but may be mottled, speckled, banded or spotted in darker shades. They are found in slow moving streams, rivers, ponds and marshes. They are predators that climb through vegetation and stalk their prey. They are probably the most voracious of all dragonfly larvae. Clubtail (Gomphidae) Clubtail larvae are robust, and have wedge shaped heads and thick 4-segmented antennae with the 3- segment extended and generally flattened, thick and club-like, while the 4-segment reduced. The antennae never develop more than (4) segments. The labial mask is not spoon-like, like other larvae but flat when view laterally. They have strong modified legs that are extended slightly to the side enabling them to borrow. The fore tarsi are 2- segmented, unlike other odonates which have (3). Their coloration is generally that of a brown to dull green. Clubtail larvae are both sprawlers and burrowers concealing themselves in the sand, mud and gravel of fast moving streams and rivers. Emergence generally takes place in a number of areas close to the water and exuviae can often be found on such structures as bridges, tree trunks and rocks.

12 Spiketails (Cordulegastridae) These larvae are cylindrical and flattened in shape and short in length. The head is broad and flat on the upper-side with a rounded shelf-like prominence between the bases of the short antennae. The labium is mask-like. The eyes are set forward on the head. The abdomen has no mid-dorsal keel, but has a well developed lateral keel. The legs are hairy, but become bare and heavily spinned near the end of the tibia and at the end of the basal segment of the tarsi. These larvae are generally brown in coloration. They are wait for prey predators and can usually be found submerged up to their eyes in sand, soft muck and silt bottom seeps or woodland streams usually where is only a slight flow of water. They are long livers and require at least 3-4 years in which to develop into adults. Cruisers (Macromidae) These larvae have a spider or crab-like shape. They are unique in that they have a protruding triangular horn on there forehead in between their eyes, and a short spoon shaped labium that partially covers the face. The entire body appears very flat and broad with a median row of high, laterally flattened dorsal hooks down the back, with short and stout caudal appendages. They have very long slender legs with their tarsi bearing very long slender and simple claws. Cruiser larvae are well concealed by colorations of mottled grays and browns. These larvae are sprawlers, and inhabit bottom sand and silt in the shallows of lakes, streams and rivers. They sprawl in the bottom debris and wait for prey to come their way. These larvae emerge at night crawling onto vegetation or structures such as bridges, docks and buildings and emerge while vertical. Emeralds (Corduliidae) Emerald larvae are generally short and robust, with wedge shaped heads and a spoon-like labium with a labrial mask that covers the face almost to the eyes. They have long sharp spines running down the back and top to the terminal end of their abdomen, with long protruding legs. The labial palps are toothed or notched distally. Those of Libellulidae remain distally smooth throughout development. This characteristic can be an aid in differentiating the two. Some larvae species to this family are sprawlers, where they lie on the sand or soft muck in woodland stream bottoms waiting to ambush unsuspecting prey, while others are climbers making there way among vegetation looking for prey. The sprawling

13 species are generally of dark coloration, while the climbers appear smooth and patterned with browns and greens. Generally larvae inhabit bogs, fens, ponds and small lakes. Emerald larvae can very easily be confused with skimmer larvae due to their shape and coloration and can only be accurately identified by using a good text with a larvae key. Skimmers (Libellulidae) These larvae are generally stocky, wide and short. They appear to have a wide head with a spoon-shaped labium that covers the lower half of the face. The abdomen is adorned with a coating of fine hair. They are generally camouflaged in colors of green, olive and shades of brown. The majority of skimmers are sprawlers with only a few species that prefer to burrow in mud. They inhabit ponds, lakes, ditches and almost any body of water. DAMSELFLY LARVAE Broad-winged Damselflies (Calopterygidae) Larvae of broad-winged damselflies are relatively long, thin and large. They are easily identifiable by their long antenna. The first segment of the antenna is longer than the combined length of remaining antenna. The prementum is with a diamond shaped medial cleft. The terminal end of the abdomen has three long leaf-like gills (caudal gills). The lateral lamellae are longer than the middle lamellae. These larvae are dark in coloration and inhabit edges of slow streams and rivers. They can often be seen climbing through vegetation. Spreadwings (Lestes) Spreadwing larvae are very long and thin. All segments of their antenna are approximately the same in length. They have a prementum with small triangular notch. The prementum is stalked and spoon shaped. The terminal end of the abdomen presents with three leaf-like gills (caudal gills) that are similar in length. Veins in the gills are visible and perpendicular to medial line. These larvae are most common in small ponds, bogs, wetlands, and sometimes in slow weedy streams.

14 Pond Damsels (Coenagrionidae) The smallest of all damselfly larvae, with large prominent eyes and a short antenna. All the antenna segments of the narrow-winged damselflies are approximately the same length. The prementum is trianglular and stout without medial notch. The labium is almost triangular in shape. Palpal lobes terminate in 1-2 hooks. The terminal end of the abdomen presents with three leaf-like gills (caudal lamellae) all in similar length with veins that radiate diagonally from medial line. These larvae are found in rivers, lakes, streams as well as marshes and ponds. They are predators that climb through vegetation looking for prey that consists of various small animals. SOURCE:

15

16 PotholesFormicamoundlocations Burnsagearea2008

17

18