Lack of monarch butterflies shouldn't be a cause for concern just yet

Monarch butterfly
Monarch butterflies aren't being seen in the numbers typical for this time of year. (AP File Photo)
on September 30, 2013 at 5:00 AM, updated September 30, 2013 at 5:07 AM

More than a month ago I was contacted by a reader who was concerned about the dearth of monarch butterflies this summer. I told her to be patient because they were between generations and it's only the last generation of the summer that has an inbred instinct to migrate. But I owe that woman an apology because this year the number of monarchs being seen in the Northeast is paltry.

To put this in perspective, one day last year in mid-September when I was on duty at Hawk Mountain 2,806 passed by. But this year on a day around the same time I counted six. In Cape May, N.J., this year, where the annual appearance of hundreds of thousands of monarchs roosting in the trees is a big tourist attraction, they're happy to report even 100 so far. And we're getting to a time when the migration is winding down.

At this point no one can say for sure what's going on although there are lots of theories. Milkweeds are the primary host plant for monarch butterflies, but very few backyard gardeners plant them and any that survive in new developments are eventually cut down by lawnmowers. Also, insecticides and herbicides like Roundup and others work extremely well, but they indiscriminately kill all weedy plants and caterpillars. And while I'm guessing that just about everyone reading this has some of them in their home, that may not be the main problem at all.

Exactly what these low monarch numbers mean for the long-term health of the species remains to be seen. Populations of all wild animals and insects fluctuate and it's only decades of data that tell the real story. So, in other words, it's not yet time to panic. Let's wait and see what happens.

And it's not just monarch butterflies that were seen in low numbers this year, which means that the weather was certainly a contributor to the problem. When it's cold and rainy, as it was several times this past season, butterflies either don't lay eggs or the eggs get destroyed. So perhaps the lack of fall monarchs this year is just a temporary thing.

Another insect is now also being encountered in low numbers, at least here where I live, but no one is getting upset about that. It's the time of year when brown marmorated stinkbugs, the non-native stinkbug that made Allentown airport famous in the entomological world, get into homes wherever they can and hide in dark nooks and crannies.

When I closed the curtains on the deck door the night before I wrote this, there were 20-30 of them hiding in the folds, although that wasn't a lot compared to what we've seen in years past. So I picked a few up and threw them out, being careful not to touch their scent glands, but I quickly decided the handheld vacuum would do a better job.