---

Terrible small photos, but maybe someone will recognize the behavior.

These flies were numerous around some gregarious sand wasps (Crabronidae: Bembicinae), and entered their holes when the wasps were not present. The wasps were, I believe, Stictia signata.

Any thoughts about the family of fly?

U.S. Virgin Islands (St. Croix), sandy beach about 15 meters from the ocean beach. Sand with patchy grass.

I believe (by memory) the flies were about 3-4 mm long.

---

Another photo, showing the entrance to the wasp burrow.

---

Hi, my first thought was Chloropidae. And indeed, it seems that your picture fits well to Liohippelates known as cleptoparasitic on Stictia signata.
Regards
Xylo

---

Thanks, Xylo. Looking further into my files, I found a better photo and notes that the length was 2.2 mm to the wing apex.