Name This Issue Thread

[Raintree]

Starting a thread to help sharpen our ID skills and knowledge. Post a good picture of an insect, insect activity, disorder or disease. You must know what it is before you post, look for unusual issues.
The goal is to educate, it's OK if you have to research and it's great if you know from experience. I'll go first, what is this?

 

[pdqdl]

Possibly Paraclemensia acerifoliella, the Maple Leafcutter Moth.

The larvae cut out a circular "tent" on the leaf, and then move around to feed, skeletonizing circular spots as they remain covered, undoubtedly for protection from predation.

https://en.wikipedia.org/wiki/Paraclemensia_acerifoliella

​

"The larvae feed on the leaves of Acer and sometimes also Fagus, Quercus, Betula and huckleberry species. Older larvae cut two circular portions of a leaf and bind them together as a portable case. They have a brownish thorax, black head and translucent whitish abdomen. Larvae can be found from June to September. The species overwinters in the pupal stage on the ground inside the portable case. "​

From another source:

"The maple leafcutter spends most of its life on or surrounded by a maple leaf. From spring through summer, when it feeds and grows, a leafcutter chews two discs of maple – each no bigger than the diameter of a pea – and fastens them together with silk so they will serve as a protective casing. It’s a bit like a pita bread with a caterpillar inside, or, better yet, a turtle with two shells. The casing is formally known as a habitaculum.​

​

A habitaculum is not a bad hideout from warblers and other songbirds hunting the trees for a squishy meal. It allows the caterpillar to feed on the remaining maple leaf without being so obvious to predators. In fact, as the caterpillar grows, it adds larger discs of leaf to its habitaculum. These discs aren’t particularly big, because, fully grown, a leafcutter caterpillar is only about one-fifth of an inch long.​

​

That was a good test! I've never seen or heard of this little bug. Fortunately, I'm not bad at figuring these things out. They seem to be more prevalent in your area.

The only distribution map I've found is from a moth photographer's website:



I would guess they can be found anywhere sugar maples are a prevalent tree species. Canada has a webpage dedicated to this relatively harmless pest.
https://tidcf.nrcan.gc.ca/en/insects/factsheet/9365
They suggest burning the leaves in the fall to prevent or reduce re-infestation.

 

[Raintree]

Excellent pdqdl, it is the maple leafcutter moth, you nailed it. Good information you posted, I learned a few new things about the moth. This insect is mostly cosmetic in its impact on maple, however customers are curious about the leaf markings.

 

[pdqdl]

Next challenge? I'll put up a test.

It is June, and you get a call from a customer: "My tree is dying! All the leaves are falling off. Upon arrival, you see this.





What's up, and what do you tell the customer? What service do you sell the customer to compensate you for your professional evaluation?

 

[Raintree]

That's a good one, keeping the maple theme going. I'll hold off on the ID to give other guys a chance to chime in.

 

[TheJollyLogger]

I'm going with sawfly larva, if it's June.

 

[pdqdl]

Could you be a bit more specific?

https://en.wikipedia.org/wiki/Sawfly

"The name is associated especially with the Tenthredinoidea, by far the largest superfamily in the suborder, with about 7,000 known species; in the entire suborder, there are 8,000 described species in more than 800 genera."​

​

That being said, this is of interest with respect to sawflies:

"The primary distinction between sawflies and the Apocrita – the ants, bees, and wasps – is that the adults lack a "wasp waist", and instead have a broad connection between the abdomen and the thorax. Some sawflies are Batesian mimics of wasps and bees, and the ovipositor can be mistaken for a stinger."​

 

[TheJollyLogger]

We just called them sawflies...let me look em up

 

[TheJollyLogger]

I guess they would be maple petiole borers

 

[pdqdl]

https://extension.umn.edu/tree-and-shrub-insects/maple-petiole-borer

Life cycle: There is one generation per year. Maple petiole borers live through the winter as pupae in the soil and emerge as adults in spring.​

• Adults lay eggs in the petioles (stems) of maple leaves in the spring.
• After larvae hatch, they tunnel into leaf petioles and feed there for 20-30 days.
  • This tunneling causes leaves to fall, often very suddenly.
• Larvae remain in the part of the stem still attached to the tree until it drops after about 10 days.
• Larvae then exit the petioles and burrow into the soil to form pupae.

So how are you going to save the tree?

 

[TheJollyLogger]

I never saw them actually kill a tree

 

[Raintree]

So how are you going to save the tree?

The tree doesn't need saving. Maple petiole borers do not affect the health of the tree or its appearance. It's best to do nothing except charge the home owner a consultation fee.

 

[pdqdl]

What if they have more money than sense, and really, really wish to protect their tree from future damage?
They don't want their tree to suffer, and it's really important!

Not only that, but their twin daughters are getting married underneath that tree next June, and they don't want it raining leaves on the wedding bliss. (that's a hint, BTW)

 

[Raintree]

I have never written a script for control of this borer. If the customer insisted even after being educated on the insect. I would go with a pyrethroid application in the spring. Possibly Tempo to achieve some population reduction with no guarantees.

 

[pdqdl]

Spring applications if timed properly should be effective, but there might be a better way. Hmmm... How would you get insecticide inside a leaf's petiole?

 

[Raintree]

If you're hinting at an imidacloprid application. Controlling larvae in the leaf stem may give you a tree full of dead hanging leaves. I think going after the adults would be best. It wouldn't hurt to do both, then again no experience here. How about you?

 

[pdqdl]

Controlling larvae in the leaf stem may give you a tree full of dead hanging leaves.

How would that cause death of leaves?
Here's the deal: Imadocloprid is a root-absorbed systemic insecticide. It is also one of the preferred insecticides for grubworm treatments in lawns, and the timing of the application is a very good match for the grubworms as well. IF I had a customer that seriously wished to do some control measure for the relatively harmless petiole borer, I'd sell a treatment that was going to provide some additional benefit that wouldn't necessarily just be taking the customers money for no gain. Fogging the tree with insecticides isn't what I would prefer to do, although I'm not entirely sure that grubworm treatments aren't in the same league. Earthworms are important, too, and I am fairly certain that imadacloprid has a toxic effect upon the earthworms.
https://scholar.google.com/scholar?...rrelation+to+active+ingredient+per+acre&btnG=
To avoid that earthworm toxicity, any decent systemic insecticide should protect against an insect that dwells in the soft tissues of a tree, whether injected or sprayed.

And no. I have no experience with any sort of treatments for petiole leaf borers.

 

[pdqdl]

Next problem? We seem to have beaten that petiole borer to death.
Myself, I am notoriously weak on my knowledge of all the various fungi that afflict the trees. Except for a very few diseases, I have found that it doesn't make much difference what the diagnosis is for any given fungal disease, the treatments are invariably ineffective once the problem is observed.

Raintree, ol' buddy, how 'bout you school us up on some maple diseases?

 

[Raintree]

Wait, wait I still have a stick in my hand and the horse is twitching. My thoughts, the adult borer ovipositor punches into the petiole. Egg hatch, consume and tunnel through the stem until it is controlled by the systemic treatment. Thus weakening and or killing the leaf. (Hanging dead leaves) Think of the damage done to twigs from the cicada egg laying activity.
Control of ground grubs would be warranted if the grubs were feeding on roots and damaging the tree. Eliminating them from the small area under the tree has very little impact on the entire population. I can suppress Jap beetle grubs in my lawn but still have to spray my peach trees for the adults. This was my inexperienced reasoning for targeting the adults in the target tree.

 

[pdqdl]

I guess it all depends upon whether the ovipositor or egg kills the leaf at the petiole, or whether the emerging larvae do. We'll probably never know until you try it out and keep us advised, because I just don't ever see them in this area.