Giant Sweet Potato Bug

Giant Sweet Potato Bug By Merle Shepard
Giant sweet potato bug. Photo by Merle Shepard

The most important host of giant sweet potato bug (Spartocera batatus), appears to be sweet potato, after which it was named. Other hosts include tomato, eggplant, potato, and Solanum nigrum, as well as avocado and citrus.

Identification
A Florida Department of Agriculture Department of Plant Industry inspector found a large colony of giant sweet potato bugs in June 1995 on an Asian cultivar of sweet potatoes in Homestead. This find represented the first report of S. batatas in the continental U.S. Subsequent surveys have found the insects sporadically and in 2007 a large colony was found on ornamental sweet potato in Naples.

Adults are a very large obvious bug with a nasty odor. They are entirely dark brown and range from ¾-inch to 1 inch in length. Lateral angles of the pronotum are rounded and without teeth, and the lateral margins of the pronotum are not expanded. Newborn nymphs are red. They soon lose their bright color and become very dark brown except for the head, the lateral angles of the pronotum, and the expanded lateral edges of the abdomen, which are marked with bright red-brown spots. Eggs are shaped like tiny fat sausages, and their color varies from gold to brown with age.

Survival And Spread
Observations in Florida indicate giant sweet potato bug adults sometimes disperse in high numbers. Thus, transient adults could be collected on a wide variety of plants.

The pest potential of S. batatas in Florida is currently unknown. It is unlikely that it will prove to be a serious pest. In Puerto Rico, S. batatas is abundant, but is not considered to be a major pest, even on sweet potato. Although S. batatas is reported in citrus, there are no reports of damage.

Giant sweet potato bugs have been found in Florida on Asian cultivars of sweet potato grown for their tender shoot tips rather than for tubers as well as ornamental varieties and in home garden situations. The damage to plants often is severe, indicating some sweet potato varieties may be susceptible to serious injury. In some cases, nearby commercial fields of sweet potatoes were not infested suggesting that damage may depend on plant variety. It remains to be seen whether S. batatas will become a pest in commercial fields.

Management Methods
Based on experience controlling squash bugs on pumpkin and winter squash, control may prove to be difficult. Adequate control depends on timing of pesticide applications so that young nymphs are exposed to the insecticide. Efficacy data on specific materials are not currently available.