You know, being an entomologist, I usually don't notice or maybe pay too much attention to the insects in my own backyard. I feel like the public gets more of the strange insect explosions and incidences than I do. But this weekend - it actually happened to me! We had a huge explosion of ladybugs congregating all over our garage.
There were literally hundreds of ladybugs congregating on the side of our home that faces the morning sun! When I got to work this morning, low and behold, many of you had experienced the same thing.
Here's what probably happened. During winter ladybugs will nest under the eaves of houses, little cracks and crevices, and other nice, tight, hiding places. When we had a day of warm, sunny weather, those ladybugs probably emerged from those hiding places to take advantage of the warm weather. They were congregating in the sunlight because it's warmer. You may have also noticed that they congregated fairly close together - this is because insect communicate by using chemicals called pheromones, which they 'smell'. They attract one another to the same area using an aggregation pheromone (also explains why you may randomly see many, many insects clumped together in one location - someone found a great spot, and they are sharing the news).
The wet and dark weather was back today and we are expected to have another week of cold weather, so don't expect to see those ladybugs come out again until we have another warm and sunny day. Next time we do - check out the sunlit side of your home and see if the ladybugs used your house to hide through the winter!