giant lichen orbweaver

not listed

NNR - Unranked

not listed

Giant lichen orbweaver is a medium-sized typical orbweaver. It occurs in the United States and southern Canada east of the Great Plains. In Minnesota it is common in the northeast third of the state, mostly absent in the rest of the state. It is found from April to September on the trunks of trees in forests and woodlands and on their edges.

Adults are variable in both size and coloration. The female can be ½″ to 1⅛″ (13.19 to 28 mm) in length and has a ⅝″ to 2″ (15 to 50 mm) legspan. In the north it is usually no more than 11⁄16″ (18 mm) in length.

The front part of the body (cephalothorax) is much smaller than the abdomen. The upper side (carapace) has a longitudinal furrow in the middle. It is dark brown and has no markings but is often paler toward the center. The underside is dark brown with a pale, branched, longitudinal stripe in the middle.

There are eight eyes arranged in two parallel rows of four eyes each. The rear row is curved forward, the front row is straight or slightly curved backward. All of the eyes are small, but the median eyes are larger than the lateral eyes.

The abdomen is large, oval, rounded, and highest in front. There are two low rounded humps in the shoulder (humeral) area. The color on the upper side is variable but the pattern is not. The base color is usually pale green, sometimes dark brown. There is a leaf-shaped marking (folium) in the form of two dark zigzag lines beginning behind the shoulder humps and converging at the spinnerets at the tip of the abdomen. Between the lines there are usually three or four pairs of irregular dark blotches. The front of the abdomen is green at the base, dark brown above, with a broad white longitudinal stripe and several white spots of varying size. At the rear of each humeral hump there is an irregular horizontal white band.

The legs are short and spiny. The front two pairs project forward, the hind two pairs project backward. They are mottled brown with dark brown rings. The last segment (tarsus) on each leg has three claws at the tip, though these are not visible to the naked eye.

The male is much smaller, just ¼″ to 7⁄16″ (7.00 to 11.52 mm) in length.

Female Body Length: ½″ to 1⅛″ (13.19 to 28 mm)

Male Body Length: ¼″ to 7⁄16″ (7.00 to 11.52 mm)

Legspan: ⅝″ to 2″ (15 to 50 mm)

A circular, 3′ to 4′ in diameter hunting web is constructed at night on the trunk of a tree. The web is a closed hub called an orb, which gives the family Araneidae its common name. The spokes, extending from the center to the edges, are not sticky, but the circular threads winding to the center are sticky. A retreat is constructed nearby. The spider sits in the center of the web at night but spends the day in the retreat.

Forests and woodlands, and edges of both.

April to September

Sources

29, 30, 82.