Eastern Tent Caterpillar
Malacosoma americanus
Forest Tent Caterpillar Malacosoma disstria  

Eastern tent caterpillars become a pest when they feed of deciduous trees, primarily  Pecans, Mulberries and Box Elders. They construct a tent of silk on one or more branches of the tree. The tent provides protection against weather and predators. The caterpillar feeds during the day, and at night, they return to the safety of the tent for protection. The caterpillar is approximately 2 inches long, hairy and black with cream colored stripe down its back. Blue spots , as well as, brown and yellow lines can also be seen along the sides of the caterpillar’s body.  
The life cycle of the eastern tent caterpillar consists of egg, larva, pupa and adult stages. In July or August, the female adult, a reddish - brown moth, lays numerous eggs (up to 300) on a branch. The eggs are held together by a sticky substance, and the following late spring and throughout the summer when the eggs hatch into the larval stage. It is the larval stage (caterpillar) of the life cycle which causes the most damage. In approximately 5 to 7 weeks, the caterpillars reach maturity, spins a cocoon and pupates for two weeks.

Eastern Tent Caterpillars on a
small nest in a Crabapple Tree

After emerging as an adult, it mates and lays eggs within 24 hours  producing only one generation per year. 
One or two colonies can completely defoliate a small tree. Periodic, major out breaks result in numerous colonies in larger trees which can also do considerable defoliation. Since this defoliation occurs, the tree must set out new leaves at considerable energy expense.

Mechanical Control - Destroy egg masses and nests. Chemical and Biological control, spray with an insecticide diazinon, dursban, orthene or methoxychlor, and again my preference is to use the biological application of “B.t.” Bacillus thuringiensis  applied as a foliar spray while the caterpillar is in the early stages of development.
Additional Images of western tent caterpillar, Malacosoma californicum:

Click on a photo for the full view

Light yellow to yellow brown. Forewings are crossed with  two lines with space in between often darker to form a band.

Larvae feed without building a tent. Spin cocoons in trees     in one or more webbed together leaves.
 (Note: The common tent building caterpillar around s

 is probably the western tent caterpillar,  Malacosoma californicum).


  Dark brown with bluish head and blue to blue-black sides.
  Dorsal surface marked with whitish or yellowish keyhole
  shaped spots and patches of orange lines.

Click on photo for the full view


Dark brown with bluish head and blue to blue-black sides. Dorsal surface marked with whitish or yellowish keyhole shaped spots and patches of orange lines.

The Western Tent Caterpillars

Click on a photo for the full view

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Genista Caterpillars  |  Canker Worms  |  Oakworms | Oak Leaf Roller

Disclaimer:   These three articles on Cankerworm, Bagworms and Tent Caterpillars may contain pesticide recommendations that, are subject to change at any time. These recommendations are provided only as a guide. It is always the pesticide applicator’s responsibility, by law, to read and follow all current label directions for the specific pesticide being used. If any information in these recommendations disagrees with the label, the recommendation must be disregarded. No endorsement is intended for products mentioned, nor is criticism meant for products not mentioned. The Writer assumes no liability resulting from the use of these recommendations.   

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