Emerald Ash Borer
Gypsy Moth, Fall Webworm & Eastern Tent Caterpillar
Tar Spot Disease 

Emerald Ash Borer

Emerald ash borer is an exotic beetle that was discovered in southeastern Michigan near Detroit in the summer of 2002. The adult beetles nibble on ash foliage but cause little damage. The larvae (the immature stage) feed on the inner bark of ash trees, disrupting the tree's ability to transport water and nutrients, in turn, killing the tree. Emerald ash borer probably arrived in the United States on solid wood packing material carried in cargo ships or airplanes originating in its native Asia.   In order to help communities and homeowners impacted by Emerald Ash Borer infestations causing dead and dying ash trees, and to properly contain and control the movement of these materials, Michigan has established sites where all parties may drop off ash trees/materials free of charge. Click here for more information on the disposal site location in Waterford Township.Larva in fall Larval gallery Adult Beetle Ash tree with dieback

Larva in fall

Larval gallery

Adult Beetle

Ash tree with dieback

Gypsy Moth, Fall Webworm & Eastern Tent Caterpillar

The gypsy moth is found in every county in Michigan's Lower Peninsula and in certain areas of the Upper Peninsula. When feeding, the gypsy moth caterpillar can leave trees stripped of foliage.  Caterpillars eat leaves of several hardwood trees including oak, birch, basswood, apple and aspen. Unhealthy trees are weakened when defoliated, making them susceptible to other insects and disease problems that can kill them.

Gypsy Moth Larva

Gypsy Moth Egg Mass

Gypsy Moth Adult Female

Often confused with the gypsy moth are the fall webworm and tent caterpillar.  Fall webworm is one of the more common late season caterpillars in the upper Midwest. It is well named with the large webs becoming evident as fall approaches. The caterpillars produce the webbing that encloses leaves, branches and sometimes entire trees. This species is most common in the central U.S. where it feeds on walnuts, hickories, American elm and many other hardwood species. In the northern portions of the Great lakes region it is more commonly observed on fruit trees including wild cherries.

Fall Webworm Nest

Fall Webworm Larva

The eastern tent caterpillar is more a nuisance than a threat. While heavy infestations can cause serious defoliation, eastern tent caterpillars rarely kill trees except those already weakened by disease or climate and environmental stresses. These caterpillars get their name from tent-like nests that they spin in the crotches of host trees. These are very neat and do not enclose foliage.  They occur early in the spring.

Eastern Tent Caterpillar Nest

Eastern Tent Caterpillar Larva

Eastern Tent Caterpillar Moth

Tar Spot Diseas

Tar spot is caused by a fungus that infects the leaves of maple trees and causes raised black spots to form on the upper leaf surface.  The diseases are caused "tar spots" because their appearance so closely resembles droplets of tar on the leaf surfaces.  Tar spot is rarely serious enough to threaten the health of the trees but sometimes there can be so many spots that the trees becomes unsightly.  Heavy infections can also cause early leaf drop, a circumstance that causes the greatest concern to property owners.  However, the tar spot fungus is not known to cause long term damage to the trees.