Butterflies are "cold-blooded." Basically, they do not use internal methods to heat their bodies and their body temperature varies with that in their surroundings (the scientific term for this is they are a "poikilotherm"). The source to heat their bodies comes from something external to their bodies (the scientific term "ectotherm" applies)(humans are endotherms, which mans we produce our heat internally, and homeotherms because our temperature is regulated by our body). Chemical reactions occur faster in warmer temperatures - reactions such as digestion and muscle movement. If your surroundings are cold and you are ectothermic and poikilothermic, your chemical reactions are slow. This means you cannot moooove very fast and your digestion is slooooow.
How does this apply to managing butterflies? Well, if a butterfly's muscles don't work well on a cold morning it cannot fly. So, the butterfly must warm up in order to fly. Usually, they crawl out from under the vegetation or out from the crevices in the bark of a tree where they roosted for the night and walk to a place where it is sunny so they can warm up. This is when you see them spreading their wings and placing their bodies in a direction where their wings will soak up the sun. You may have noticed that butterflies that were fluttering about on some cool days all of the sudden go to the ground or on vegetation when the sun goes behind a cloud. They are having a difficult time keeping warm enough to fly. You'll notice them spreading their wings and waiting for the sun to come out and warm them again.
One way to help butterflies warm their bodies is to place an object that heats quickly and maintains its warmth for a while in their vicinity. The butterflies can move onto such an object and warm up quickly, even when the sun is behind a cloud. A rock, especially a flat one, serves this purpose well. Placing some in your butterfly garden will help the butterflies on cool or cold days.
Why is it so important for them to warm up quickly? They are "sitting ducks" for predators when they are waiting to warm up and cannot fly! Thus, the rush is on for them to find some place warm on a cold day.
Did you know some butterflies overwinter as adults? Once they get cold, they cannot move well at all and if they get too cold they will die. One way to help them is to provide some type of cover or place for them to hide while they wait for Spring to arrive. An example may be a pile of logs. Butterflies are known to get inbetween logs that are close together and spend the winter. Under leaves is a good spot for two reasons. First, it is difficult for predators to find them. Second, the leaves slowly rot and this process gives off some heat. This helps keep the butterflies from freezing to death. I believe butterfly boxes or "houses" were designed not only for a place to hide during the night but also one to over-winter. Many people who have owned these tell me they don't attract butterflies. I believe the reason is the space in the box is too large. These boxes would likely be used more if the inside consisted of boards placed very close together but large enough for a butterfly to crawl between them. A design similar to a bat box but on a much smaller scale would likely work better. Anyone want to experiment with one like this and a regular one placed in the same location to determine which would receive more use?
Be careful about warming butterflies or anything that is "cold-blooded." All of these animals have an ideal body temperature. They try to keep their bodies near this temperature by moving into warm places when they are cold and into cool places when they are hot (sounds like me). They will die if you put them into a place which is too cold or too hot for too long. A good example is when a child places a butterfly in a jar and accidentally leaves it in the summer sun. Even a jar with some breathing holes can get scolding hot in the sun, especially if the top is metal. Both glass and metal will get very hot and this heat will radiate into the air in the jar. You can literally cook a butterfly or other cold-blooded animal in this manner. Many a child has accidentally killed animals by leaving them in the car too long on a warm, sunny day. Obviously, you know what the sun does to the inside of a car on a warm day. Anything used to warm them must allow them to move away from it when they are warm enough.
I'll talk about bees in the next post. You might be surprised why it is important to provide for them as well as the "cute" animals such as butterflies.