Unwelcome tent campers...

Something bright caught my eye as I drove through the woods, causing me to stop the car and check it out. It was about mid-way up the tree, just about eye level. As I approached, I could see a web of silk filled with small, dark caterpillars spanning the fork of a maple sapling branch. I recognized it as a tent caterpillar, an insect that is capable of totally defoliating a tree. There are two species in Pennsylvania; Eastern Tent Caterpillar Malacosoma americanum and Forest Tent Caterpillar Malacosoma disstria. Eastern Tent Caterpillar arrives in the spring, while Forest Tent Caterpillar returns in autumn.

It's important to make the distinction, because one is worth controlling while the other is not. Any time a deciduous tree is defoliated early in the growing season, it's more serious than if it occurs later. Just as squirrels store food before winter, trees store food in their roots during winter. This provides the energy needed to leaf out in the spring. Once leaves unfold, trees begin manufacturing their own food again (carbohydrates and sugars) through the process of photosynthesis. When autumn frosts arrive, trees send this food back into "root storage".

If a tree is defoliated by tent caterpillars as the foliage appears in spring, it's forced to leaf out a second time before its had a chance to make more food. This process depletes food reserves even further and leaves trees vulnerable if there is additional stress during the growing season. Think other insects, hail damage, frosts, diseases - any number of things can happen.

If caught early, and the tent is within reach, you can either squish the insects in their tent or prune the tent out. If the tent occurs where structural branches connect, is out of reach, or you are squeamish about the squish factor, consider spraying with Hot Pepper Wax. There's no need to wait for the insects to emerge from the protection of their tent at night to spray. Simply saturate the tent with Hot Pepper Wax Insect Repellent any time during the day and these caterpillars will be "fumigated" within their tent.

With rare exception, there's no need to spray the Forest Tent Caterpillar that appears in the fall. Since they damage trees just before they'd naturally drop their leaves, the trees have already made enough food for winter and won't be seriously hurt. No major harm means no control needed and more time to enjoy your garden.

Eastern Tent Caterpillars - May 2012

Maples pay a price for spring color...

This has been a spring to remember if you live in the northeastern United States. March broke high temperature records causing spring flowering bulbs and trees to bloom almost a month early. April was drier than normal and alternated between warm days and freezing nights. then as our native trees greened up, they morphed into a rainbow of color! In addition to the normal soft greens of spring, a cheery red appeared against blue skies.

While we expect an array of color in autumn, bright red maples in spring demanded a closer look. Anticipating I'd find tiny red flowers (though a bit confused because I know maples normally flower with the daffodils in our area), I was surprised to see that the red coloring was due to a heavy crop of samaras or seeds - aka "helicopters". Closer inspection of the maple in my front yard revealed the same thing, only in green.

I spent a couple of weeks blissfully enjoying the view until I was reminded that there will be consequences. I remembered fielding calls about "sick maple trees" in mid-summer years ago. People were concerned because their trees were thin on top and appeared to be dying. The trees had produced so many seeds in the spring that they didn't have enough energy left to produce a full leaf canopy. This was not an insect or disease issue (and trees weren't dying), but rather the result of perfect weather for maple seed production.

So is there anything we can or should do? Not right now - except to hope we don't get a secondary stress this summer. If the weather turns dry this summer and you can provide water to a specimen tree, do it. Most importantly, fight the urge to fertilize until the fall. Doing so now or during the summer will actually make things worse, though a little fertilizer this fall will give your tree a head start for next year.

Meanwhile, I'm going to enjoy the flight of the samaras that I know is coming while I add an extra cleaning of my rain gutters to my summer "to do" list.

Spring color as trees leaf out - April 2012

Red Samaras

Green Samaras