After stunningly warm temperatures in mid-March, Nature hit the pause button and produced lower than normal temperatures for more than a week. That hasn’t been enough to halt the onward march of plant development.

Trees are leafing out four weeks early and the insects that eat them are hatching too.   Tent worms are a case in point.

Eastern tent caterpillars (Malacosoma americanum) feast on trees in the Rose family, especially wild cherry, apple and crabapple.  Last summer the female moths laid their egg masses on the branches of host trees.  The eggs remained dormant all winter and then, just as the hosts’ buds began to swell, the eggs hatched and the larvae began to spin their tents.  In the past this happened in early May.

This year I saw the first tiny tent on April 1 at Moraine State Park.  A week later I found this much larger tent crawling with activity.

Most birds won’t eat tent caterpillars because they retain cyanide from the host plants but cuckoos eat them with relish.

Black-billed and yellow-billed cuckoos spend the winter in South America and time their arrival to coincide with the emergence of eastern tent caterpillars.  A few yellow-billed cuckoos have been seen in the Gulf Coast states but the bulk of them aren’t in North America yet.  The leaves and tent caterpillars are four weeks ahead of schedule but the cuckoos are not.

What will happen to the cuckoos when the tasty caterpillars they expect to find have retreated to cocoons?  What will happen to our trees if this causes an excess of caterpillars?

Nature is out of synch.  Some things can cope, some cannot. We’ll just have to wait and see.

For more information on climate change’s effects on bird migration listen to this interview with Powdermill’s Drew Vitz on The Allegheny Front.

(photo by Kate St. John)