Another saga : pecan tree aphids ... (long)

roselee z8b S.W. TexasJuly 26, 2012

Late last summer/early fall my pecan tree had a horrible infestation of aphids. One problem with aphids is the sticky honey dew they exude which covers leaves, furniture, walks, and drifts even beyond the canopy of the tree. A black mold then grows on it making every thing look like soot has settled. The odd thing is I don't remember ever having aphids before. The pecan tree was very small when we moved here, but has benefited from the water and fertilization of the lawn and is now a medium size tree.

Why after all this time did the aphids come in such high numbers? And then early this summer it starts again ... sigh. I looked on-line and saw various insecticides recommended, but I rarely use killer chemicals and besides I couldn't get them up into the canopy of the tree even if I wanted to.

Natural controls include lady bugs (would they go up there if I bought and released them?) lacewings, spiders and other insects including wasps. Wasps!

Then I remembered Malcolm Beck's account of a pecan tree farmer who had never had a webworm problem until the owner's nephew spent the summer and for entertainment knocked down all the paper wasp nests with his sling shot. The next year the farmer had a huge outbreak of webworms and realized that the wasps had been keeping webworms under control. Caterpillers are the number one food that wasps feed their larva.

In the spring of 2011 I planted lots of butterfly larva plants. I went all out. And to give the butterfly larva the best chance of survival I started knocking down paper wasp nests. I felt kind of bad about it, but I didn't use insecticides and kill them. I just knocked the nest down when they first started building. I left just one or two for old time's sake. You see, I called them my pet wasps.

Paper wasps are non agressive by nature. They were all over my greenhouse/tool shed, but I was rarely stung and then it was only a pin prick. I could reach right next to them and they just watched. But even if I accidently bumped the nest they just gave me a tiny little warning buzz and a bounce off my arm. Wasps are not called the geniuses of the insect world for nothing. Because I was in and out of the shed all the time they were used to me and recognized me as harmless. Now when Bob bumped a nest he got stung so I usually got any tools he needed because I didn't want to hear about how I should get rid of the wasps.

Even so 2011 was going to be my raising butterfly year. But because of the drought the butterflies never came. I saw maybe a total of ten butterflies all last summer and none laid eggs on the plants I'd provided for them.

This year the wasps built a lot of nests and I let them stay. There were a few Gulf frit caterpillars on the passion vine, but only a few, and nothing showed up on anything else. However, the wasp larva have to eat something and their nests looked to be full of larva.

So guess what? The aphid outbreak seems to be over as quick as it started. As usual I can see wasps drifing around high up in the canopy of the pecan tree. I always thought they were taking care of the webworms before they got big enough to make a web but now it seems they were also taking aphids for their larva to eat. That's my take on it anyway.

The paper wasps are staying :-)

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wantonamara Z8 CenTex

I always leave them unless they are inside the home. interesting theory.

    Bookmark   July 27, 2012 at 10:37PM
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Lynn Marie

Nice story. I bet you are right. So, to get butterflies, you have to have aphids too? I wonder how far away the wasps hunt? Maybe you could get a neighbor to plant butterfly bait and they would fly to your yard once they morphed???

    Bookmark   July 28, 2012 at 11:37AM
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roselee z8b S.W. Texas

Mara and Lynnmarie, it looks like the wasps and perhaps other beneficial insects have taken care of the aphids. No more honey dew, thank goodness!

Lynnmarie, I guess I would say to not have aphids a few butterfly larva have to be sacrificed to the wasps. Wasp predation is why some people take the larva and raise them in cages. However, the wasps don't get them all. In years past I've had quite a butterfly larva survive, make it to chrysalis stage, and hatch. I'm not sure how far the wasps roam, but yes, with their permission, I do plant butterfly larva plants in my neighbors yard :-)

    Bookmark   August 4, 2012 at 2:15PM
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patty_cakes

I haven't been on the forum for quite a while and come back to find a thread that's quite useful to me~~i've had what i've been calling an infestation of wasps(paper???)on a Live Oak this weekend. There must be aphids also, as when I left my car in the drive when I came back from San Antonio this weekend, and went back out to it a couple of hours later, it looked to have a slight sticky spray of some sort all over it, out door light fixtures also. I'm assuming it's the aphids all of you are talking about?? I haven't had a 'close inspection' of the tree because of the wasps, but should I leave both the wasps and the aphids, and let nature take it's course since the wasps use the aphids as larva food? This is all so very enlightening. Thanks roselee! ;o)

    Bookmark   August 7, 2012 at 6:21PM
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patty_cakes

I haven't been on the forum for quite a while and come back to find a thread that's quite useful to me~~i've had what i've been calling an infestation of wasps(paper???)on a Live Oak this weekend. There must be aphids also, as when I left my car in the drive when I and went back out a couple of hours later, it looked to have a slight sticky spray of some sort all over it, out door light fixtures also. I'm assuming it's the aphids all of you are talking about?? I haven't had a 'close inspection' of the tree because of the wasps, but should I leave both the wasps and the aphids, and let nature take it's course since the wasps use the aphids as larva food? This is all so very enlightening. Thanks roselee! ;o)

    Bookmark   August 12, 2012 at 5:11PM
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roselee z8b S.W. Texas

We had a pecan tree limb blow down last week and I thought, 'Oh goody. I can inspect the leaves.' I found a very few very tiny yellow aphids, about one on a leaf of every 5 or 6 leaves I looked at with a magnifying glass. So they are there, but not enough to cause a problem. It's seldom that nature eliminates every bug by natural means, but there is definitely control. So yes, let nature take its course and most things stay in balance.

    Bookmark   August 13, 2012 at 12:05PM
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patty_cakes

Thanks roselee, the wasps seem to have calmed down, and I didn't do a thing. Need to take another look today to check on aphids, and hope I don't see any or will have to invite the wasps back! ;o)

    Bookmark   August 14, 2012 at 1:58PM
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