Crambus

The eggs of Crambus species are dry and nonadhesive, with an oval to elliptical shape. The eggs of most species are white to creamy white when first laid, but later turn bright orange or red. The size of the eggs varies between species, but ranges from 0.3 mm to 0.6 mm.[3]

The color of the larvae also varies from greenish to beige, brown, or gray, with most larvae having dark, circular spots that extend over the entire body. From the first instar to the third instar, the head capsule will appear black, but later instars have a light brown head capsule with various black sculpturation. At the first instar, the head capsule is 0.19–0.23 mm wide, growing to 1.23–2.21 mm by the last instar. The length of whole larvae is 9–13 mm (0.4–0.5 in) at the first instar and 24–28 mm (0.9–1.1 in) at the last instar.[3]

Crambus larvae, known as "sod webworms", feed primarily on grasses. In turfgrass species, their primary host plants are cool-season grasses, with fewer records on warm-season grasses. Some species also feed on maize, wheat, rye, oats, timothy-grass, and other grasses in pastures, and meadows, with the most damage occurring in areas with permanent sod. The damage caused is more pronounced during times of drought.[4]

The pupa develops in a silken cocoon attached to soil particles, plant debris and fecal pellets. The cocoon resembles a small lump of earth, while the pupa itself is pale yellow at first, darkening to a mahogany brown. The pupae are 8–10 mm (0.3–0.4 in) long by 2.5 mm (0.1 in) wide.[3]

The adult moth is whitish or light gray to tan. Many species have patterns of colors, including silver, gold, yellow, brown and black. The moths are approximately 12 mm (0.5 in) long, with wingspans of 20–25 mm (0.8–1.0 in).[3] Like other snout moths, they have long labial palpi that extend in front of their heads, and fold their wings underneath their bodies, making them slender and harder to see while resting on plants.[3]

To be considered a serious infestation of sod webworms, 12 larvae must be found in a 0.1 square metres (1.1 sq ft) area.[3] To test this, hollow pans are placed with a pyrethrum or detergent drench and allowed to sit for 10 minutes, then the larvae in the area are counted. During peak growing periods, the grass will often be able to recover by itself and not show serious damage. For high-end turf that cannot show any damage or serious infestations, predators of the sod webworms must be attracted, including birds and insect predators, such as ground beetles, robber flies, and predatory wasps. The larva is also prone to infection from microorganisms such as Beauveria bassiana and Nosema (Microsporidia). Parasitic nematodes such as Steinernema carpocapsae and Heterorhabditis heliothidis can also infect sod webworms.[4]