Boxwood Leaf Miner - Monarthropalpus flavus (continued...fly stage)

In an earlier post, I captured photos of small Boxwood Leaf Miners- Monarthropalpus flavus (boring worms) that feed between boxwood leaf tissue.  In this post, I captured the worms, now emerging as pupae, transforming into adult flies.

Here, the leaf miner begins its emerging life cycle, by exiting through a hole and developing a pupae which hangs on the underside of last years leaf. Last year, adults laid eggs to overwinter in the tissue of the leaf. Eggs hatched in late April and began munching away until its time to begin the process of becoming a winged adult fly.

The leaves on the right, are last year's. On these leaves, you can see the pupae coating sheath which the adult fly shed. Once the fly cracks through this, it emerges and sits a while, until its wings have dried enough for flight.

I sat a while at the sight of all the activity. Flies buzz around, mate and then find the new flush of boxwood growth. They fixate their bottom end to the underside of the new tender leaves and poke holes - inserting their eggs for the next generation.

The flies time it perfectly. The tender new leaves have soft tissue, easy to poke their eggs into.

Interestingly, when it's windy, the flies have little success attaching their egg laying bottoms to the leaf. You can easily swat them away at this point.

I noticed this process has gone on for about two days. It's now late May, we've had brilliant sunny days and I suspect another day or two and all the egg laying will be done. Many adults were dead and left hanging up-side-down. It's a pretty short adult life span.

Best to prune the tips of growth a week or two after this process is complete. This removes the eggs and then the boxwood will respond with putting on new growth without any adults left to lay more eggs.

Neat process to witness entirely. Have a look at my previous post on Boxwood Leaf Miners - the worm stage.

Boxwood Leaf Miner - Monarthropalpus flavus

My eyes were drawn to my small Korean Boxwood yesterday. This variety is called "Green Gem". I bought it 3 years ago. It had some winter snow (weight) damage on it earlier this spring, but something else caught my attention.

Seeing these brown blisters frustrates me.

Tucked inside these blisters is a creature called: 
Monarthropalpus flavus - Boxwood Leaf Miner

As you can see, pretty much all the leaves have blisters in various stages of  the leaf miner's life cycle.

Here, I brought a stem inside to reveal what's inside each blister pocket. 

The adult leaf miner lays eggs, by inserting them between the layers of the boxwood leaf. Making a perfect pocket situation for their offspring to hatch, become pupae and begin feeding.

Here you can see the small puncture hole mark, 
where the adult laid the egg. This hole becomes the exit for when they pupate into adults.

Some leaves have 3-4 miners munching away. Getting ready to become adults.

On the shiny, upright part of the leaf, you see more browning and damage. Holding this up to the light will reveal the pupae, its excrement and the ever enlarging pocket they create.

These photos show pupae that are orange, this means they are near ready to transform themselves into adults. The pupae are lighter in colour when young - more yellow. Once they become orange, this is the time they stop feeding and go through their next life cycle. Through the puncture "window" or hole, they will squeeze through, hang from upside down until they pupate into an adult - orange fly.

This is an insect that is hard to control, unless you cut back the blistered portions of the boxwood ruthlessly or if you use pesticides. Systemic insecticides would help me combat this insect, but for such a small plant and for the sake of spraying chemicals, I choose not to in this case. In Ontario, one would require a pesticide license to acquire such chemicals to do the trick.

Since this is a young boxwood, I have decided to take it out of my garden. If I prune it back hard, it will take a long time to recover and my garden is too small to waste space. Last year the leaf miner numbers were unnoticeable to me. Perhaps I purchased this boxwood with leaf miners or perhaps not. Best rid this boxwood before it feeds off my other plants.

So sad.... Time for something else in that spot.

Have a look at my post on the adult-life-cycle of this Leaf Miner.