The eastern tent caterpillar (Malacosoma americanum)

UPDATE: June 20th

Our lilac has a bite out of most of its leaves. All is well, though. They have cocooned!

UPDATE: June 8

They are massing on trees to do their instar, again!

UPDATE: An interesting article!

Oriole, eating tent caterpillars! A lot of birds do NOT eat them, since they cannot digest their furry shell.

May 27th
As we travelled to Chesterville and Long Sault, I noticed a lot of forest tent caterpillars. Then, I spotted some here at home!

The pupate a couple of times, and grow larger.


From Wiki:

Under field conditions, the caterpillars feed three times each day, just before dawn, at midafternoon, and in the evening after sunset. During each bout of feeding, the caterpillars emerge from the tent, add silk to the structure, move to distant feeding sites en masse, feed, and then return immediately to the tent where they rest until the next activity period. 

The exception to this feeding pattern occurs in the last instar, when the caterpillars feed only at night. The insect has six larval instars. At the last stage, the caterpillars disperse and each constructs a cocoon in a protected place. The adult moths, or imagoes, emerge about two weeks later. 

As the weeks passed, they started marching towards the house. Seriously! All on the porch, headed towards the front porch and the door.



The forest tent caterpillar moth!

The is the adult moth

They lay eggs on branches, which overwinter.

Egg casings are laid in August.

References

This was on Google. Heaven knows where it is from!

ENTFACT-423: Eastern Tent Caterpillar  |  Download PDF

Sometimes people confuse the fall webworm with tent caterpillars.

Natural Controls (Back to Top)

A wide variety of factors have been implicated in causing population declines, including several adverse environmental conditions. High levels of larval mortality have been associated with relatively low temperatures in the winter and spring (such as a late or hard freeze following larval emergence) and harsh weather when early instars are abundant. Harsh weather and extremely high temperatures may kill numerous adults later in the spring, and also reduce mating success and viability of offspring amongst survivors. Outbreak populations may also decline or collapse as a result of starvation, when larvae exhaust food supplies (i.e., host foliage) before completing development (Drooz 1985).

Natural enemies such as parasites, predators, and diseases may also exert important regulatory effects on Forest tent caterpillar populations. Some natural enemies are often extremely abundant during the later stages of outbreaks (Drooz 1985). The documented natural enemies of tent caterpillars are numerous, including 14 species of Hymenoptera egg parasites, 52 Diptera and 61 Hymenoptera species parasitic of larval and pupal stages, and 18 Hemiptera, nine Coleoptera and one Dermaptera that are predators of various life stages (Witter and Kuhlman 1972). At least 18 species of the parasitic insects have been recorded in Florida (Frank and Foltz 1997), as well as a parasitic nematode in the family Mermethidae.

Other known predators include frogs, mice, skunks and over 60 species of birds (Witter and Kuhlman 1972). Bird predation of late-instar and pupal stage forest tent caterpillars has recently been demonstrated to cause overwhelming mortality of populations at all densities in an artificial setting, and is hypothesized as the principle regulator of low density populations between outbreaks (Parry et al. 1997).

Forest tent caterpillars invading Winnipeg, says entomologist

CBC.ca

Rochon says forest tent caterpillars typically infest the city once every 10 to 15 years, but when an infestation hits, it can last two to three years.