I recently spent a week in San Diego California for a course that was required as part of my work. Since it was below freezing when I left, and snowed here in Iowa while I was gone, I was sort of amused by the weather reporters complaining about how cool it was there. It got down to 40 degrees F at night and in the day the highs were in the sixties. I wore a sweatshirt at night and jeans and a short-sleeved shirt during the day.
One of my co-workers asked me if I had seen any butterflies there (because he knows just how weird I am). The thing is, I did watch for butterflies and for other pollinators.
I saw one monarch and three honeybees. And that was all. No syrphid flies, no other bees, no other butterflies, nothing. I did see one hummingbird though.
The places I went were all covered with asphalt, concrete, buildings, and roads. There were some small flower gardens that mostly had wood mulch in them. And I was there when they had unseasonably cool temperatures.
Even with the cooler weather, there should be more insects in the environment. It is possible to almost entirely eliminate them. And in spite of what many people think, that is not a good thing.