Walnut caterpillar

Datana integerrima Grote and Robinson Lepidoptera: Notodontidae)

Orientation to pest

Walnut caterpillar, Datana integerrima Grote and Robinson, is a native North American notodontid whose larvae feed on walnut (Juglans), butternut (Juglans cinerea L.), pecan (Carya illinoinensis [Wangenh.] K. Koch), and hickory (Carya tomentosa [Poir.] Nutt.). It is found in southern Ontario (Canada) and throughout the eastern United States. Adults fly in spring and summer and lay their eggs in masses on the undersides of the leaves of the host plants. The larvae feed gregariously until almost mature and are often seen in masses on the trunk and larger limbs, where they congregate to molt. Mature larvae drop to the ground and wander before pupating in the soil. There are one or two generations per year, depending on the location.

Hosts commonly attacked

This caterpillar feeds on walnut (Juglans), butternut (J. cinerea), pecan (C. illinoinensis), and hickory (C. tomentosa).

Distribution

The walnut caterpillar is found in southern Ontario (Canada) and throughout the eastern United States.

Images of walnut caterpillar

Jerry Armstrong, Bugwood.org 768x512 / 1536x1024	Lacy L. Hyche, Auburn University, Bugwood.org 768x512 / 1536x1024	Lacy L. Hyche, Auburn University, Bugwood.org 768x512 / 1536x1024
Figure 1. Adult of walnut caterpillar, Datana integerrima	Figure 2. Eggs of walnut caterpillar	Figure 3. Larvae (middle instars) of walnut caterpillar

Jerry A. Payne, USDA Agricultural Research Service, Bugwood.org 768x512 / 1536x1024	Jerry A. Payne, USDA Agricultural Research Service, Bugwood.org 768x512 / 1536x1024	Lacy L. Hyche, Auburn University, Bugwood.org 768x512 / 1536x1024	Lacy L. Hyche, Auburn University, Bugwood.org 768x512 / 1536x1024
Figure 4. Larvae of walnut caterpillar feed in groups	Figure 5. Walnut caterpillars aggregating on branch for molting	Figure 6. Leaf skeletonizing by young larvae of walnut caterpillar	Figure 7. Complete defoliation of small tree by walnut caterpillar

Important biological control agents related to this pest species

Known parasitoids of the walnut caterpillar include Telenomus ichthyurae Ashmead and Tetrastichus sp. in Texas.

Web links for information on walnut caterpillar

• Forest Insect & Disease Leaflet 41 | USDA Forest Service
• Digital Diagnostics Fact Sheet | Oklahoma State University
• Species Recognition and Habits Guide | L.L. Hyche, Auburn University
• House and Landscape Pests Publication | AgriLife Extension, Texas A&M System

Articles

• Tedders, W. L. and H. C. Ellis. 1977. Aerial application of Bacillus thuringiensis var. kurstaki (HD-1) to shade and ornamental pecan trees against Hyphantria cunea and Datana integerrima. Journal of the Georgia Entomological Society 12: 248-250.
• Farris, M. E. 1978. Bionomics of the walnut caterpillar, Datana integerrima G. & R. Urbana, Il: University of Illinois, Dissertation.106 pp.
• Farris, M. E. and J. E. Appleby. 1979. The walnut caterpillar, Datana integerrima G. & R., pp. 22-28. In: Anon. Walnut insects and diseases, workshop proceedings. General Technical Report NC-52. U.S. Department of Agriculture, Forest Service, North Central Forest Experiment Station, St. Paul, MN.