Per Grok 4.3:
The insect in your photo is a stonefly (order Plecoptera).
Key identifying features visible in the image:
•Wings: Two pairs of large, elongated wings with a very dense, net-like (reticulate) venation pattern — hundreds of cross-veins forming small polygonal cells. This is a classic trait of stoneflies. The wings are held relatively flat over the body (typical resting posture for the order).
•Abdomen: Long, slender abdomen ending in two long cerci (tail-like appendages) visible at the posterior end. Stoneflies always have two cerci (mayflies usually have three).
•Antennae & legs: Long, thread-like (filiform) antennae and long, slender legs.
•Coloration & markings: Mottled gray-brown wings with darker veins and lighter patches; a distinctive yellowish-orange mark on the side of the thorax (common in many species).
•Overall body shape: Elongated and somewhat flattened, typical of adult stoneflies.
Likely family
Given the size, wing shape, and intricate venation, this is most likely a member of the family Perlidae (common stoneflies) or Pteronarcyidae (giant stoneflies). Without a precise geographic location or closer view of the head/terminalia, species-level ID is difficult, but it is definitely not a mayfly, lacewing, dobsonfly, or caddisfly.
Quick facts about stoneflies
•Nymphs are aquatic and live in clean, well-oxygenated streams/rivers (they are excellent bioindicators of water quality — their presence usually means the water is healthy).
•Adults do not feed much (some don’t feed at all) and live only a few days to a couple of weeks, mainly to mate and lay eggs.
•They are harmless to humans — no sting or bite.
If you can tell me roughly where the photo was taken (country/region or habitat — near a river, lake, etc.), I can narrow it down further to genus or species!