Seasonality
for Fruit Fly
Fruit flies can stay active indoors year-round wherever food ferments, but their numbers track temperature: UC IPM notes egg-laying stops below about 54°F and above about 91°F, with development best in the low 80s°F. Populations swell as the season warms and ripe or culled fruit grows abundant, so kitchen problems often peak in late summer and fall. Source: https://ipm.ucanr.edu/agriculture/strawberry/vinegar-fly/