The timing for Walnut Caterpillar Moth reproduction affords some protection for popular nut trees.
Walnut Caterpillar Moths are a rich brown color with 3 pale lines crossing the wings. When viewed from above, the pale lines's curves resemble ripples. Hindwings are rounded and ivory in color. The furry thorax has a dark, reddish brown crown. The puffy nature of the thorax almost overtakes the head like a giant collar. The moth is on the wing from April through autumn.
The caterpillar for this species gets more attention than the adult. The black caterpillar has a black head and is covered in long, wispy, white hairs. Depending on its maturity, thin white lines may run down the length of the body, which can also appear maroon or red. They are often seen on tree branches in large congregations, crawling over each other and surrounded by caterpillar silk. The overall appearance may take the shape of a white, fuzzy ball. The web-like silk ball and clustering behavior resembles the kind seen in webworms, but that is a different kind of caterpillar. Walnut Caterpillars do not sting and do not bite. They may wiggle with their heads raised in an attempt to scare off a predator, but they lack an irritating defense typically seen in many other hairy caterpillars.
Bare patches in a leafy tree are signs of caterpillar feeding. As the name suggests, Walnut Caterpillars eat the leaves of walnut trees. They also eat from pecan, butternut, and hickory trees. While many caterpillars on one tree can defoliate it at an alarming rate, they usually feast in autumn, when trees are fortunately in the stages of storing energy and not making it through their leaves. This means that the impact of the feeding is less harmful, especially for nut production, than if this species were to start feeding in early spring. In warmer parts of its range, three broods can be produced in one year. The earlier in the season the caterpillars feed, the more harmful it is to the tree's health and ability to produce nuts. Parasitic insects and predators naturally control the caterpillar, but insecticide use and manual removal of caterpillars also reduces the likelihood of annual outbreaks.
Scientific Name: Datana intergerrima
Butterfly or Moth
Size (Adult; Length): 21mm to 28mm (0.82in to 1.09in)
Colors: brown; tan; white; ivory
Descriptors: white stripes; dark brown head; flat head; flying
Note: An insect's reach is not limited by lines drawn on a map and therefore species may appear in areas, regions and/or states beyond those listed above as they are driven by environmental factors (such as climate change), available food supplies and mating patterns. Grayed-out selections indicate that the subject in question has not been reported in that particular territory. U.S. states and Canadian provinces / territories are clickable to their respective bug listings.
Butterfly and Moth Anatomy
Antennae: Butterflies and Moths have a pair of antennae on the head used as sensors.
Head: The head is home to the insect's eyes, antennae, and proboscis.
Thorax: Home to the three pairs of legs as well as vital internal organs.
Abdomen: Contains vital internal organs such as the heart(s) and reproduction facilities.
Forewing: The upper, forward wing pair used for flying.
Hindwing: The lower, rearward wing pair used for flying.
NOTE: Butterflies and Moths are part of the Lepidopteran order as they share many similarities.