Holes and fuzzy white balls on plum prune leaves

Plum and prune    OH Zone 6

My prune plum tree's leaves are being eaten by something which I have so far been unable to identify. There are ragged holes in many of the leaves and there is also many white fuzzy balls on the leaves that look like they may be egg cases of some sort. I have attached a few pictures of the damage. Does anybody recognize it? What can I do to rid my tree of this pest? Thanks

Posted by: Rosemarie (2 points) Rosemarie
Posted: August 6, 2013

David Hughes commented,
i updated my answer
over 7 years ago.


You have skeletonized leaves on your plum tree which would be caused by a lepidopteran pest (moth or caterpillar) or beetles. Other insects like grasshoppers eat from the edge inwards.
Skeletonized as it sounds it because the insect eats the tissue between the veins of the leaf leading to a skeleton. Have a look for caterpillars or beetles (also at night).

Your tree is fine and can withstand this damage.

You would need to find the culprit before deciding what to do. The fuzzy balls might be either caterpillars or spiders. They may not be doing the damage.

You can control by wiping the leaf with a soapy cloth pulling the fuzzy balls off. If you can determine the culprit is a moth/butterfly then you could use an organic solution like Bt spray which is from a bacteria that produces a toxin that kills lepidopterans http://en.wikipedia.org/wiki/Bacillus...
This would have no effect on beetles.

Regarding the other suggestion by Peg. The mealybugs are very different and dont chew/bite leaves. They have sucking mouthparts like a syringe that they stick into the leaves to suck out liquids which the ingest. The do have associations with ants who protect them in return for sugar (they are bodyguards). You might have these and do check, but they have not caused the holes in the leaves.

Here is an email I receievd from Dr David Biddinger, Fruit Tree specialist at Penn State

"I think these are the pupae of parasitoids of chrysomelid or cigar casebearer (Coleophoridae) larvae than were doing the damage much earlier. Most probably ichneumon or braconid wasps of some sort. The damage looks old with all the feeding pest larvae gone, but these pupae would persist for awhile. Chalcids also commonly attack the larvae of chrysomelids. The cocoons most remind me of Dinocampus (Braconidae) that attack adult Coccinelidae. Hard to really tell without better photos or actual specimens. Pretty sure they are not egg cases unless they would be for spiders. Hope this helps. David"

So, the fluffy things are good. They help killed the beetles damaging your plum trees. No need to treat anything as the beetles are gone now

Posted by: David Hughes (55 points) David Hughes
Posted: August 6, 2013

Peg Boyles commented,
Duh. For sure nobody's gonna hire me for their backyard entomology consultant.I made the classic mistake of (maybe) identifying an insect pest, but not the pest that's causing the pictured damage. I don't grow fruit trees, but I should know better. I'd better stop commenting on questions about insect damage.

But David, do you think Japanese beetles might have eaten the holes in the plum foliage? It does look like their kind of damage.

over 7 years ago.

David Hughes commented,
Peg, you were correct to put up your idea. That is how PV can be powerful. No problems if it didnt hit the mark, I also had that on other answers. The questioner and the hundreds/thousands of other reading benefit to see our thinking on these questions.

Yes, could really be Japanese Beetles

over 7 years ago.

I don't recognize it, but here's a list of possibilities (assuming Ohio's pests are similar to California's) in the right-hand column:

Posted by: Tanya in the Garden (128 points) Tanya in the Garden
Posted: August 6, 2013

I think you have an infestation of mealybugs. http://bit.ly/13DL79w I've had them on houseplants and seen them on various field crops, though never on plum. But there are many species of these sucking insects, and they can be pesky to control.

The females of some species secrete the telltale cottony layers to protect themselves while they suck the juices from plant tissues, and as a protective tent under which to lay their eggs and protect their young.

All species of mealybugs secrete honeydew, which can cause a fungal infection called sooty mold that looks just like it sounds. You may see ants scurrying around on the infested leaves. I think I see a black ant in the photo on the far left. Adult ants eat honeydew. http://bit.ly/14wIbyj

They actually farm aphids and related insects such as mealybugs http://www.youtube.com/watch?v=wE1X_Q..., protecting the smaller insects from natural predators so they can continue "milking" their farm animals for sustenance. Amazing!

Insecticidal soap is the usual means of control for the soft-bodied aphids and mealybugs, but may cause toxic reactions in plums. http://bit.ly/13KHKtR Test a few leaves first to see how it affects them; if you see leaf damage, try diluting the solution.

Posted by: Peg Boyles (3 points) Peg Boyles
Posted: August 6, 2013

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