On summer nights, you can see swarms of insects around the light.
Written forms
群がりUsage100%
Standard kanji spelling for this noun form.
叢がり
rarely-used kanji form
Rarely used kanji form; 叢 is an uncommon character for 'cluster' or 'thicket'.
簇がり
rarely-used kanji form
Rarely used kanji form; 簇 is an uncommon character for 'swarm' or 'crowd'.
Etymology
Noun form of the verb 群がる (mura-garu), which is derived from 群 (mura, 'group') + suffix がる (garu, 'to seem, to be inclined to'). The kanji 群 means 'crowd' or 'group'.