Other similar caterpillars
Several common caterpillars, that show up fairly regularly in Iowa, are often confused as being gypsy moth caterpillars. Here are some of the more common caterpillar defoliators and a brief description of their habits and host preferrences. This information may help you determine if you are looking at a gypsy moth caterpillar.
Click on the pictures to get a larger more detailed view of the insect. To learn how to identify gypsy moth in all of its life stages, please visit our Gypsy Moth Identification page.
Eastern tent caterpillar (Malacosoma americanum) appear in the spring, and are the species most often confused for gypsy moth in Iowa. Caterpillars hatch about the time when crabapple trees are in bloom which is about 3 to 4 weeks earlier than gypsy moth. Damage from eastern tent caterpillar is usually noticed in the month of May.
Tents from caterpillar groups can be quite extensive; although, they are contary to gypsy moth. Gypsy moth caterpillars do not produce tents, or have extensive webbing. Preferred hosts include wild cherry and plum, apple, hawthorn, and crabapple. Eastern tent caterpillar will also occur to a much lesser degree on ash, birch, willow, maple, oak, and popular.
Fall webworm (Hyphantria cunea) appear late summer and can produce extensive webbing in trees. This is contrary to gypsy moth since gypsy moth caterpillars only appear during May through June and do not produce silken webs.
There are blackheaded and a redheaded color forms of fall webworm, and both are commonly found in Iowa. There are about 100 tree hosts, but preferred hosts include walnut, hickory, birch, cherry, crabapple, and linden.
Whitemarked tussock (Orgyia leucostigma ) is perhaps the most common of all tussock moths. Caterpillars begin to be noticed in the month of May through July. There may be anywhere from one to three generations of tussock moth per year. Caterpillars are general feeders that skeletonize leaves, leaving only the leaf veins, but generally do not cause wide-scale defoliation.
Tussock moths are hairy, but are quite different in appearance when compared to gypsy moth. There are at least 60 host plants that the caterpillars will feed upon. Preferred hosts include maple, horsechestnut, birch, apple, sycamore, poplar, and linden.
Forest tent caterpillar (Malacosoma disstria) are not as common in Iowa as the eastern tent caterpillar, however they have similar life cycles and appear during the same time of the year. They can be serious defoliators in woodland and urban situations; although serious outbreaks haven't been noticed in Iowa for quite some time.
Forest tent caterpillar may be noticed more in woodland areas of southern Iowa, and along the Mississippi River. Their range extends from coast to coast and from Florida to Canada. Instead of producing a silken tent, such as the eastern tent caterpillar are known for, they will collect together in large groups and will produce a silken mat on the trunk of the host tree.
Gypsy moth caterpillars will never produce silken tents or mats. Forest tent caterpillar have a variety of hosts, but the preferred hosts include ash, birch, basswood, sugar maple, oak, and poplar