Download high resolution image here.
I found this larva in a hollowed-out seed of a
Juniperus deppeana (Alligator Juniper) "berry" (berry-like cone) at
35°10'03.2N 106°22'31.2W, 7328 ft. elevation,
Sandia Crest 7.5’ quadrangle, along Sulfur Canyon Picnic Ground Rd. in the
Sandia Mountains, Bernalillo Co., NM.
The berry shown is about 9 mm in diameter. It has been cut in half with a razor blade to reveal the larva within the top left chamber. One sees in this image an anterior view of its head. The second image is a close-up of the first. The larva has been excised for the third image, showing its dorsal view. I examined many such berries from this tree. Many had such a larva present, or at least had chambers apparently having been hollowed out and full of frass by a prior one (like the other three chambers shown here).
After taking live shots, the specimen was soaked in 95% ethanol, then acetone, then HMDS
(1), then acetone again for at least 24 hours each. The
acetone was then rapidly evaporated with intense light from a 250 W dual fiber optic microscope illuminator to minimize shrivel. The last three images are of the specimen so treated. The prolegs with crochets identify the larva as
Lepidoptera, as opposed to a sawfly.
Three species of
Periploca (Cosmopterigidae) are known to inhabit juniper berries in the western U.S.
(2). Only one (
P. atrata) is known to inhabit
Juniperus deppeana (Alligator Juniper)
(2). That is in neighboring AZ. The ventral view of the pupa's abdominal tip is used by Tonkel et al. 2019
(2) to distinguish the three species. I went back three weeks later and found one within a berry of the same tree:

This confirms that it is
P. atrata.
The species does not appear to have been reported in NM, so I have preserved a fragment of another larva excised (unsuccessfully) in 100% EtOH for genetic ID, if needed. I will also collect branches periodically and place them in water in an enclosure. If any adults eclose I will post images. The pupa did not survive, but retained its appearance upon desiccation, so I am keeping it as a specimen.