Got Birds? Have Fewer Insects

by Rich Baer, Portland Rose Society, Master Rosarian

It is the beginning of February and time to really start getting serious about thinking about the New Year. But for a minute, I want to reflect on last year. Whereas the overall effect of the garden last summer was beautiful and the growth seemed to be fantastic, with many of my roses growing well over seven feet tall, there were some unusual happenings. The amount of disease that I tolerated in my garden was probably the most I have had in a number of years. I know that much of that was probably due to a change in the weather pattern, and part of it was my inability to maintain my antifungal spray schedule as I have in the past. It is not that I did not spray, but that the garden disease pressure was higher than in past years, or least that is the way it seemed. We would usually get black spot in the early part of the year during the rainy season and then mildew when the rain stopped. Finally during the warmer parts of the summer, rust would become pervasive in the garden. This past year the rust appeared early and stayed in the garden for the entire growing season and it seemed to resist my attempts to slow it down.

There was one thing that usually showed up in the garden that I found interesting in its absence. That was the presence of insects. Throughout the entire summer I encountered very few insects of any type in the garden. I do not remember seeing any of the green leaf eating worms, Orthosia hibisci, which I routinely collected every morning during my early walk through the rose garden. There were just none to be seen. In addition, it was not until late in the season that I saw a few (three) stems with aphids on them, another quite unusual situation. And with the absence of the aphids there also were no beneficial insects to be seen. Early in the year there were a few lady bugs in the garden, but they were quite small in size as compared to what they usually looked like. There also were no hover flies, (syrphid flies) nor any of their larvae. Beneficial insects need prey insects to feed on to keep up their populations, but with no pest insects in the garden the beneficials did not show up either. Personally, I missed seeing most of them throughout the season because they have always been there. I admit that rarely do I intervene against any insect invasion that I see in the garden. About eighteen or more years ago I decided to no longer use any general insecticide sprays in the rose garden. I have found that in the intervening years small problems have come and gone, but I do not think that I have lost any significant part of my rose crop to any particular insects during that time. (Rose midge may be one exception to that overall experience. But this insect is not one that the average rose gardener ever complains about.)

There may be an explanation about the absence of insects in my garden and it may even be that I am playing a significant part in their absence. During the last year, my budget has included several hundred dollars for various kinds of bird food. I feed many birds on a regular basis because I love looking out the kitchen windows and seeing numbers of various types of birds in our front yard. Many of them are attracted to the various kinds of seeds, especially the sunflower seed that is in two of our large birdfeeders. But there is an equal number or more that are attracted to the suet seed cakes that are in the five feeders that are hanging in the front yard. Seed eating birds keep pretty much to a diet of seeds throughout the entire year. Insect eating birds, however, usually cannot switch to eating seeds although some enjoy both seeds and insects. We have a fairly large flock of lesser goldfinches which consume a great quantity of sunflower seed. They may prefer thistle seed but they accept sunflower seeds gratefully at our feeders. There are a number of other small birds which are present such as the nuthatches, Bewick’s wrens, and chickadees, both black capped and chestnut backed. Both of the latter have a diet that contains both seeds and insects. The largest number of one species in our garden is the Bushtit (Psaltriparus). Our local flock numbers somewhere between twenty and thirty individuals. They pass through the garden several times every day and occupy all five of our suet cake feeders and they come and go quickly between the feeders and the surrounding vegetation that actually counting them is not possible. I have never seen one on either of the seed feeders, although they are known to eat some seeds in their wild diet. I try very hard to maintain all of these birds in our area during the winter season when there is very little natural food for them to eat, so that they will still be here when there is food to eat. Bushtits are known to very voracious eaters of small insects including leafhoppers, aphids and almost other small insects. I see them passing through our garden in the summer time in their straggling flocks all through the warm season except for the time when they are nesting when they quit their flocking nature and appear as individual pairs. Over the years, I have seen their nests in the garden in various places and they have rather large numbers of offspring generally 4-10. They do this in a remarkable large hanging nest. So, maybe this is the single most likely cause of our garden being without many, or what seems like no, insects during the summer. All of these birds eat vast number of insects every day during the summer season, each with their specific favorites. While the bushtits take care of the aphids, the chickadees seek out the green fruit worms very vigorously. I watched a nesting box in the garden one day and the adults came with great regularity to feed their chicks and every time one landed on the nesting box it had a caterpillar in its beak so they were finding and removing a tremendous number of green worms from the garden every day.

Two other birds that you might not think of as being insect predators are our two local species of hummingbirds. Generally we seen them feeding on the nectar of various flowers in the garden and I plant a number of plants in the summer just for them. When they are not visiting flowers they are supplementing their diet with dozens of small insects and spiders daily. However, I try to keep a hummingbird feeder hanging in the garden throughout the winter as well. It allows the locals to survive the winter which is difficult for tiny birds like the hummers. I say that I use no insecticide in the garden, but perhaps I should claim all of the bird food that I buy during the winter to maintain the flocks of predatory birds so that they can be my summer insecticide.

Photos by Rich Baer