Aphids, how many is too many?

                                        Microsiphum aphids on rose bush

I read somewhere (I wish I could find that reference now) that the aphid biomass in an acre of meadows can be equivalent to that of an elephant. Perhaps that is a gross exaggeration, but, even if it was comparable to the mass of a cow or a dog, that is a lot of aphids. Let us face the facts: aphids are here in our gardens in substantial numbers, whether we see them or not. I am sure that I have eaten my share of them on leaves of lettuce, and you have done so too.

Is that a bad thing? Probably not, as long as there are only a few per plant. They don’t cause serious damage and they form part of the food chain, nourishing numerous kinds of wildlife, small and large. Aphid populations can be kept in check by the combined action of all those eaters most of the time. It is a beautiful system when it works well, but sometimes it gets disrupted.

Ecologists explain repeatedly that trouble often arises when pesticides wipe out not just the aphids, but their predators. Predator populations take longer to recover, allowing newly arrived aphids to explode in numbers before balance is reestablished.

I have been looking for these aphid controls in my garden. There is a whole assortment. Usually ladybugs take most of the credit, but others are just as effective or even more so, although less visible: parasitic wasps, flower flies and lacewings, among others. Some small birds, such as nuthatches and chickadees have been seen eating aphid eggs in winter.

Syrphid fly larva feeding on aphids

Syrphid flies, also called flower flies or hover flies interest me the most because they provide another important service in the garden: they are pollinators. The adult flies spend a lot of time hovering over flowers. They land on them to feed on pollen and nectar and to meet partners and mate. Their two common names refer to these behaviors. They look very much like bees, giving rise to amusing mistakes of which I have collected a few illustrations: a book named “Bees of the World”, a business card for a shop called “The Bees Knees” and an article on bees on the French newspaper, Le Figaro. In all these cases the image is not that of a bee but of an impersonator, a fly. If you know of any other examples, please let me know, so I can add them to my list.

The larvae of some of them, those called Syrphini, feed on aphids. The females are very good at spotting incipient populations of aphids and laying their eggs nearby. When the maggots emerge from the eggs they go right to work and can dispose of dozens of aphids in the ten days or so that it takes to complete their growth.

To learn more about their life cycle I collected some, kept them well supplied with aphids and saw them grow to full size, become pupae and finally emerge as adults. I took pictures and videos of the whole thing. The videos may be gross but fascinating. A maggot blindly thrashes around until it finds an aphid, pierces its skin and proceeds to suck it dry, discarding the shriveled husk. The whole process takes only a few minutes. It resumes its search right away. No wonder they can be so good at controlling aphid populations!

Another form of trouble occurs when new species of aphids are introduced into an ecosystem. This doesn't happen intentionally, but aphids easily travel with their host plants and may be able to adapt to related plants found in their new home.

Oleander aphids on milkweed

Such is the case of the oleander aphid. It has adapted to plants of the genus Asclepias, the milkweeds, and it can wreak havoc on them. It multiplies in large numbers, free from its habitual restrains. A few species parasitize of predate on oleander aphids, such as some parasitic wasps and lacewings and ladybugs, but all them together are not enough to keep the populations of oleander aphids under control.

Invisible Bird Food in the Foliage

On a gorgeous end of summer day, I visited the wildflower garden of a local nature center with the intention to capture with my camera some of the wildlife, flower visitors, in particular. Unfortunately, I realized on arrival that I didn't feel well and needed to rest. So I stretched out on a bench under a gazebo, using my handbag as a pillow.

I rediscovered a simple truth: If you remain still and silent, nature comes to you and shows you things that you would have missed otherwise. A toad peeked from under the next bench, remaining in the moist coolness and shadows. Birds sang, flew, and dove into the foliage to emerge again, perhaps near me. A butterfly almost bumped onto my face.

Finally, one of those confusing fall warblers, a Wilson warbler perhaps, landed just ten feet from me. I am hopeless at identifying those drab olive and yellow little fellows. It proceeded to browse delicately from a jewelweed. I wondered what food it could find there. Some detective work was in order. I rested a little longer and then I got up to investigate.

I saw some holes on the leaves. Insects had been feeding; but they were long gone judging by the scar tissue around the wounds. Still the possibility remained that a similar leaf feeder was present when the bird landed. No way to know, though. Also, I couldn't guess whether the long-gone eater had been a caterpillar, sawfly or leaf beetle larva. My detective skills are severely limited in this respect.

Further observation led me to the mummified body of an aphid, not worthy of a bird's attention; but a clue nonetheless. Where there is one aphid, almost invariably there are more. It didn't take me long to find clusters of fat juicy green ones under the leaves of the jewelweed. I would have never noticed the well hidden aphids if the bird had not brought them to my attention.

Although I cannot be sure, I suspect that this was the morsel that the warbler was after. The insect life in the garden is rich and mostly out of sight. It feeds the birds, more skilled than us at spotting this nutritious resource. And thus, the web of life goes on.

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© Beatriz Moisset. 2012

“Locavore” Birds. Grow your own Birdseed

Are we being a bit unrealistic about this business of buying bird seed? I don’t quite understand all this farmland devoted to growing bird seed. I assume that the farmer has to prevent birds from ruining his crop. So, all and all, I don’t think that we are truly helping the birds this way. Instead, we are bringing them to our yard for our own selfish pleasure and depriving them of habitat somewhere else.
If we really wanted to feed birds in our backyards we should grow our own birdseed, rather than buying it from other sources.
I know that bird seed has become a big business in recent years. It was a very good idea at the beginning and feeding the birds continues to be an educational tool that helps people appreciate wildlife. But perhaps it has gone too far. What we really need right now is to start growing plants beneficial to birds in our own backyards: the ultimate in “eating locally”.


I began to ask myself these questions and soon realized that I am not the first one. I simply googled “grow bird seed” and found out people who grow gardens from bird seed. I also found those who despair because spilled seed keeps growing where it isn’t wanted. They seem to miss the irony on feeding the birds and fighting against growing bird seed. “Buy only shelled seed”, “nuke it in the microwave oven” they say.
Fortunately the ones that choose to grow bird seed have a lot of good advice, from discussing the benefits of growing only native seeds to the money saving aspects of such gardening. I am sure that a little planning would be very helpful. Not all the bird seed that you buy will grow in your area and not all would look pretty in your garden, but there are some that can really enhance the beauty of your garden, plus being beneficial to pollinators as well as birds.

Yes, let us grow our own bird seed! Let our visiting birds become locavores!

Feed the birds with native plants

Seed-Bearing Flowers for Birds

Don't buy birdseed -- grow it

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Feed the Birds

Goldfinches at feeder

You think that you love birds. Every week you pick up your binoculars and go birdwatching with others who share your interest. You have one or two birdhouses in your properties and, of course, bird feeders that you can see from your window while you drink your morning coffee. Yes, you are very much a bird lover.

But what would you think if I told you that you are probably dooming some birds to death and starvation through your gardening practices? Let us say that you decide to buy a new tree for your yard, you love the color and shape of Japanese maples and that is what you choose. Later on, you take a look at azaleas and rhododendrons and find out that there are some Chinese cultivars which you find extremely attractive. You bypass the native varieties and choose one of those.

These innocent actions have deplorable consequences for the birds that visit your yard. Birds have no use for those foreign plants. Well, you say, “I have seen them use those branches for nests, what could be wrong with such plants?”

Until just a year ago I would have thought exactly the same. I didn’t know the bad consequences of using non-native plants as long as they weren’t invasive. But reading a book by Doug Tallamy (Bringing Nature Home) opened my eyes to a whole new perspective and a new appreciation of how food chains work, not just in nature preserves and remote parks but in our own backyards.

A nutritious caterpillar feeding on native wild ginger

Numerous insects are adapted to native plants and find your Japanese maple and alien azalea totally inedible. So what? Who needs insects, anyway? You say. –Birds need insects; that is who! Ask yourself: what do birds eat? Particularly, baby birds with their voracious appetites and fast growing bodies? They need lots of proteins; that is why their parents spend several hours a day hunting for insects, because insects are little packages of protein. If your plants are non-native there isn’t much insect protein to be found on them and the birds have to search somewhere else.

So to put it in a nutshell, each time that you plant an exotic tree or shrub you are dooming some baby bird to hunger and death. Or, if it makes you feel better, each time that you plant native plants you are helping the birds you love, perhaps even more than you do with your bird feeders.

A handsome looking native shrub, mountain laurel

Nature centers and wildflower preserves as well as some arboretums sell native plants and can provide information on them. You can also find these regional native plant lists useful: Pollinator Friendly Planting Guide. They are intended for pollinator gardens but they can apply to all wildlife.

For the area I am familiar with, the Atlantic seaboard:
Delaware Native Plants for Native Bees

And of course, the book mentioned above: Tallamy, Doug: Bringing Nature Home and the website: Bringing Nature Home

Caterpillars are for the Birds

Have you ever seen a caterpillar hanging from a thread when you were walking through the woods? You probably have, more than once; it happens often enough that, although caterpillars are very small and not easy to see, everybody sooner or later gets a chance to see this peculiar scene.
Did you ever wonder where it was going? Certainly not up, most likely down. But, down where and for what reason?
Many caterpillars feed high on the canopy, devouring tender leaves and growing very fast. After they are done growing they start getting ready for the big transformation, called metamorphosis, which will turn the rather shapeless, wormy thing into a winged marvel, a moth.


Where you find a caterpillar there may be hundreds or thousands, all of them gleefully feeding on the same tree. Look up at the tree’s foliage above your head; there doesn’t seem to be much damage and this is very fortunate. Part of the reason is that there are many hungry creatures who regard the caterpillars as very tasty and very nutritious morsels of food. Among them you can count some of your most beloved birds, warblers, wrens, sparrows. You see them fleeting about and they may be picking up some of your caterpillar’s brothers and sisters. They will be taking them to their growing brood and ramming them down their hungry throats.
Let us get back to our question: where is the caterpillar going? It may be looking for a secluded place in the leaf litter, safe from winged predators (although not entirely safe for there are other hungry creatures in the soil too). Once on the ground it probably won’t go very far. In most cases it tries to find some leaf litter and it proceeds to bury itself in it. There it will begin spinning a cocoon using a special kind of saliva that changes into silk, strong and supple, as soon as it gets in touch with air.


It may proceed to undergo a big transformation in just one or two weeks to become an adult moth, or if it is the end of the season, it will wait until next year; hunkering down through a long and cold winter and will emerge only when the trees are already leafing out.


During that time it grows wings and legs and antennae and becomes a pretty moth ready to find a mate and to start the cycle all over again. If it is a female it will lay eggs after searching very diligently for the same kind of trees where it fed as a caterpillar.
Most caterpillars are very particular about their food; they can feed only on one kind of tree or perhaps a handful of related trees, for instance, only sugar maples or only several varieties of maples, but not oaks or ash trees. Others will choose only oaks or ash trees. They are so particular that many of the ornamental trees brought from overseas for their beautiful foliage or interesting shape are useless to them. The indirect consequence of a landscape with only imported plants is: no caterpillars - no food for the birds. If you love birds you may want to plant native trees to ensure that birds can find food hidden in their foliage.

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