What is that?

Insects and diseases of trees can manifest themselves in strange and sometimes beautiful ways. Two such examples are bagworm moths and fungal fruiting bodies. Going on a hike today? Be on the lookout!

Bagworm moths

These little critters can do a whole host of damage to your evergreen (and deciduous) trees! Named after their home, the bag-like cocoon is made of the caterpillar’s silk and the tree leaves where it is living and feeding. Bagworms tend to blend. You need to look closely to see them, especially in an evergreen.

Bagworm photo by John Ghent

The Bagworm caterpillar lives its entire life in its case, feeding on your tree and adding more room to its little home. In the summer, the caterpillar retreats into its bag, changes into pupa form and emerges as a moth. The male moths then leave their case, find a female moth (who never leaves her case!), and they mate. The female then deposits between 500-1,000 eggs in the bag-like case, falls to the ground and dies.  So, each bagworm house contains a LOT of eggs.

On deciduous trees, bagworm damage is not necessarily fatal. Usually the defoliated tree will re-leaf. On evergreen trees the damage can be fatal. Usually, by the time the bagworm problem is noticed, it is too late to treat the tree.

The best way to treat a tree with bagworm is to pick off the critters and throw them in the garbage – yes, the garbage. Do not compost or toss the bagworms into the woods. Handpicking, from late fall to early spring, will allow you to organically take care of the problem, while also taking a good, close look at your tree. Find-the-bagworm is a great activity for kids, too!

Fungal Fruiting Bodies

A fruiting body is a fungal structure that contains spores. If there are fungal pathogens infecting your tree, a fruiting body will form on the tree – on the roots, trunk or even branches. A fruiting body is the reproductive structure of the fungus. Fruiting bodies come in various sizes, shapes and colors which helps in the identification of the fungal pathogen affecting your tree. But here is the most important part: If you see a fruiting body on your tree it usually means there is advanced decay happening. Simply removing the fungus will not take care of the problem, as the fungus is inside the tree.

Fungal fruiting body on a birch limb