These appear to be symptoms of Boxwood Leafminer infestation, a very common insect pest of boxwoods (though some boxwood cultivars are more leafminer-resistant than others). The recent transplanting may have added to their stress, in part because of the root disturbance, and in part because boxwoods thrive better in semi-shade than in full sun with limited root room in containers.

You can learn about this and other typical boxwood ailments in the page linked above. Treatment for leafminer tends to involve either pruning most of the larva-infested growth off, or treating the plant with a systemic insecticide. During the heat of midsummer, larvae stop feeding and go into a sort of summer dormancy, not feeding again until later in the season, so any insecticide application made now might not be very effective, though pruning would be okay. (Pruning a plant to expose inner leaves that used to be shaded, in this case by both the pre-existing shade and also the plant's own outer foliage, could cause those leaves to get sun scald or a more orange hue from the stress of sudden sun exposure.)

Miri

Miri,

Hello Lolli,

They can tolerate full sun, and yes, are often grown by public gardens and home landscapes in sun, but are at their best with a little bit of shade. (In the wild, where they are native overseas, boxwoods of this type actually grow as woodland understory shrubs.)

If they are not scalding after a month in full sun, you're probably fine, but they will need more frequent monitoring for watering needs due to both the sun and the container than they did in their prior location. The sun exposure might be making the leafminer damage more prominent, though, since that is the tissue that will "burn" first, being damaged and thinned by their feeding. (Boxwoods don't really wilt, but they could sunscald.)

Leafminers have one generation per year. The orange gnat adults laid eggs several weeks ago, and the pale spots might be areas where young larvae were active until it got hot, as they start to blister the leaf by feeding on the inner, middle layer of tissue. The older, already-empty mines are those with the greater degree of discoloration and holes in the bottom of the leaf. (Larger holes and tears exposing the leaf mines are from predators like birds trying to peck them out to eat.)

Miri

Miri,

Leafminers have one generation per year, and the larvae are present inside the leaves from about May-June through the following spring, so any leafminers in the shrubs now likely moved along with them and didn't need to find them post-move. This is also a very common pest, and if any other boxwoods are grown nearby, they could easily have found these other plants and colonized them, though the adult gnats don't fly very far on their own.

Containers can be monitored in the same way (feeling the soil moisture level by touch) that in-ground plants are, just to a shallower depth. Monitoring depth can depend on pot size, but large containers can probably be checked around three inches down, give or take. Boxwood roots are fairly shallow, so it's not as likely that they would suffer from root rot if the lowermost levels of soil accidentally stayed too wet. Generally, taller-profile planters drain better than shallower containers, since the water table (the zone of soil holding the undrained moisture near saturation levels) will be further from the roots in a deeper pot.

Miri

Thank you,

Spinosad is translaminar, which means it's somewhat (but not quite) systemic...it can absorb into the leaves onto which it is sprayed, but won't move into new tissues that were not sprayed, which a truly systemic ingredient could to some extent (at least if it were root-applied as a soil drench). The ingredient acephate is also translaminar, but is "harsher" than spinosad and not usually recommended. A root-applied systemic containing one of the neonicotinoid class of insecticides (ingredients include imidacloprid and dinotefuran) are often used when truly systemic insecticides are needed for a pest, but are regulated by Maryland's pesticide law, so only certified pesticide applicators can apply them to outdoor plants. (They are not banned completely, just restricted in who can legally apply them.) We don't collect information on every insecticide ingredient on the market, so there may be other options, but the pesticide label needs to include directions for use on the plant in question (they might not list "boxwood" specifically, but landscape/ornamental/residential plantings or trees/shrubs should suffice as long as it's not just for use in nurseries), and also list the pest in question (like "leafminers" as a general group, if it doesn't specifically say "boxwood leafminer").

Miri