Green Spanworm - Itame sulphurea (Packard): Photo - This spanworm hasn’t been found in very high numbers thus far on Maine cranberry beds, but is capable of doing considerable harm. The action threshold (AT), however, is different from all of our other spanworms (18 per 25 sweeps).  Where it is often found in combination with other spanworms, though, I believe using an AT of 4.5 (or 9 depending on berry price) per 25 sweeps makes management easier and safeguarding the crop less risky. It is still seen in very high numbers on a few Massachusetts bogs, and in 1920 and 1921, it devastated the entire crop on a very large scale for many Massachusetts growers. [See also pages 27-28 of Cranberry Insects of the Northeast by A.L. Averill & M.M. Sylvia]

Horned Spanworm - Nematocampa resistaria: Photo - This peculiar-looking spanworm is unmistakable with its double set of dorsal white-tipped tentacles (‘horns’) on the 2nd and 3rd abdominal segments. Besides eating cranberry, it feeds on many softwood and hardwood trees and goes through two generations in our part of the country. So far, it has been found only occasionally on Maine cranberry beds.

Chainspotted Geometer - Cingilia catenaria (Drury): This spanworm is most often found in low numbers on Maine cranberry beds. It may be on the rise, however, and a very high population of moths were observed on a cranberry bed in Washington County in early October, 2004. Literature from an entomologist (Baker) from 1972 says that the species prefers blueberries, huckleberries, and small trees growing in pastures or cut-over areas. With blueberries in that list, this is a pest for us to be watchful for, and explains why it is also seen in New Jersey cranberries. [See also pages 32-33 of Cranberry Insects of the Northeast by A.L. Averill & M.M. Sylvia]

Spiny Looper - Phigalia titea (Cramer): The populations of this spanworm apparently cycle in forest stands, similar to other forest caterpillar pests, where it is typical to have several years of very low populations, followed by one or two years of extremely high populations that subsequently crash due to external factors such as viruses, fungi, lack of food, predators and parasitoids, etc. It was been reported on one Maine cranberry site in 2006, where numbers were quite high in distinct portions (patches) of the bed—highly characteristic of this spanworm—and left the infested area looking brown and burned. The larvae feed on the leaves of new growth. Some larvae nip the stem of new shoots, which then fall over. Its seasonal history has not been studied on cranberry. Over the last several years, though, it has become a significant problem for many Massachusetts growers so we may be learning more about this spanworm in the future. [See also pages 31-32 of Cranberry Insects of the Northeast by A.L. Averill & M.M. Sylvia]

Big cranberry spanworm - Eutrapela clemataria (J.E. Smith): Though only a few of these have been seen on Maine beds per season, they can be extremely destructive in small patches of a bed, resulting in fairly circular areas of damaged vines. They prefer to sever the flower buds and blossoms. Larvae appear in late June in Maine. They are dark brown with bumps across their back and grow to 2.5" in size. Spot-treating is usually the best approach if we should ever discover a problem with this particular spanworm. 
 

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