Even the healthiest yards can fall prey to the hungry caterpillar. While most of the damage occurs in the summer months, this time of the year we notice the nests they’ve left behind. With a little preventative maintenance now, you can avoid a spring surge of very hungry caterpillars.
Recently, I have noticed many of the lacy “tents” that dot the outer limbs of trees and bushes. These nests are the home of the fall webworm - a widely distributed pest of shade trees and shrubs. Hyphantria cunea, feeds on almost 90 species of deciduous trees commonly attacking hickory, walnut, birch, cherry, and crabapple. This species acts similarly to the eastern tent caterpillar (see below), but the fall webworm encloses leaves and small branches at the ends of the limbs whereas tent caterpillars make their nests in the nodes and branches of a tree's limbs.
While caterpillars make great bird food, I, for one, don’t like those nests in my yard. The pupa overwinters in a cocoon that is concealed in ground litter, cracks and crevices, or in the soil. Adults first appear in mid-June but may continue to emerge in small numbers during most of the summer. Females usually deposit their egg masses on the undersurface of the leaves. Larvae (future caterpillars) hatch in approximately 7 days. They immediately begin to spin a small silken web over the foliage on which they feed. As they grow, they enlarge the web to enclose more and more foliage, eating all the while.
At this time of year, the easiest removal is to prune those ends that have nests and either bag them in plastic or burn them.
Removing and/or burning is not quite as effective for the eastern tent caterpillars, Malacosoma americanum. Often considered pests due to their habit of defoliating trees, they are equally said to have noteworthy behaviors, among them: being social, colorful and diurnal (active in the daytime; as opposed to nocturnal, active in the night).
This species, which includes 26 different types, may defoliate an area, but don’t usually become a blight. If you’ve ever sat outside in spring and thought you heard rain falling from otherwise ‘dry’ trees, it’s this species of caterpillars defecating. Their food intake results in large quantities of output, especially as they gain size and develop in the latter larvae stages.
It’s easy to spot their silk tents in the branches of host trees. These webs are brilliant really, with lots of different chambers that make use of sunlight. Inner chambers are built for direct sun exposure and will warm up much faster than the outside air. As the season progresses and the caterpillars need cooler rooms, they move to the outside of the nest. While I can admire the solar efficiency, it also makes these nests easy to find – and, dare I say, treat.
Mechanical removal is not practical for this species. Pesticides and poisons, while effective, endanger ground water, pets and children. Plus, most of us are looking for an organic, specific solution. Dormant oils can be sprayed that will cover and smother the eggs. Dormant oils have traditionally consisted of petroleum products, but a homemade recipe using cottonseed or other vegetable oils can be found here.
The trick is to apply your horticultural oil in dormant months to the branches, leaves and roots of the plant. So often this is true of the problems in our yards and the problem in our lives, too. If we only attack our problems when they’re unsightly and visible, we will likely see their return. The key is to notice what’s happening to leaves and fruit. Are they healthy? Do you notice leaves that have been eaten? Fruit undeveloped?
How about you? Are you emotionally healthy? Do you have trouble with anxiety or addiction? Do you spend too much time thinking about the past, or obsessing over the future? Is there an underlying, maybe even hidden, issue that needs to be addressed?
I remember one summer (quite some time ago) when I heard the Lord tell me it was time to get rid of my short shorts. I listened and I put them way back in the back of my drawer. Well some time later, when I needed a little boost, don’t you know I dug back there and found them. Hesitantly at first, I put them on. I liked how they looked. I liked getting attention. It wasn’t long until I was wearing them regularly again.
Then, I heard a stronger voice: cut them up. This time, I got out my scissors and did just that. I can’t describe the freedom I gained from being obedient instead of looking to the world or to men’s attention to make me feel better. My problem was not what I wore, but why I wore what I wore. Rather than find confidence in myself, in my abilities, my lot in life (I was simply a young mom), I tried finding it from people I didn’t even know.
The Bible calls this ‘being a friend to the world.’ Simply put, any action that pleases our own pride and lusts – however big or discrete – puts us at odds with God’s best for us. While it might not kill the whole tree, it won’t stay tucked away in the cocoon forever, either. The most effective plan to remove the pest is to address it at the source, not merely the lastest expression, but at the root (origin). I love this promise from God’s word about our (most towering) strongholds.
“Yet it was I who destroyed the Amorite before them, whose height was like
the height of the cedars and who was as strong as the oaks;
I destroyed his fruit above and his roots beneath.” Amos 2:9
When we choose to address the issue in the ‘off-season,’ I believe God can and will help us eradicate those worldly pests.