Sunday, December 23, 2007

Butterflies are "Cold-Blooded"

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.


faddisfamily said...

Say you find a caterpillar in your yard -- how do you go about identifying what it is???

William R. Gates said...

Hello faddisfamily. There are a number of websites that have pictures of caterpillars (they may call them butterfly/moth larva or larvae) for identifying them (Here is one for the state of Idaho - I'd try to use one from a natural resources agency, university, museum or other site that is likely to have it crrectly identified. One in or for your state or a nearby state would be ideal. Here is a site for butterfly and moth information for North America - It has pictures of some caterpillars. In addition, you can find field guides and similar books that have pictures of caterpillars of a few of the more common species. Examples are the Peterson's or Audubon field guide series (each has at least one for moths and butterflies) and "The Butterfly Book" by Donald and Lilliam Stokes published in 1991 (a good overall guide to butterlies and butterfly gardening). Just be aware that most moth and many butterfly caterpillars will not be easy to identify by these means.

Have a great day,

Srinath Muralidharan said...

Hi William,
Thanks for the info. I am into learning macro photography and i have a great interest in butterflies. Few things i want to know from you are

1. Location where i generally find them, For e.g I have seen dragon flies wander over small water channels. Same way is there any specific condition to find butterflies
2. How to catch butterflies unharmed? I want to take very high magnification shots (5x) and i need to have them in captivity for that. But i don't want to hurt them in anyway
3. I heard that keeping butterflies in fridge for sometime slows them down and can take pictures. But does it harm it?

Thanks for your time.


William R. Gates said...

Hello Sri:

Sorry it took me a while to get back to you.

Here are my brief answers to your questions:
1. Most butterflies feed on the nectar of flowers. They will also "puddle" (drink water from wet soil), especially during hot weather. Thus, you will want to look for them where there are nectar producing flowers and where there is wet soil (for example, along streams, ponds, and lakes) in hot weather. You may attract some species by placing fruit in an outdoors location - some will feed on the juices and some even prefer the juices of rotting fruits. Some will feed on rotting meats and animal carcasses as well. Butterfly houses can be a good place to photograph them. You may be able to find all live stages (egg, larvae or caterpillar, pupa, and adult) to photograph. However, you have to look at the adults closely because many will have wing damage, etc.
2. It is nearly impossible to catch and handle a butterfly totally unharmed. The minimum that will happen is you will rub protective scales from their wings by handling them. Biologists catch them in nets on a handle. You can likely find them for sale on the internet. I'd suggest avoiding rare species since you may harm the individual. You have to handle them by the wings after catching them or they will try to flap them and likely do damage to themselves.
3.Yes, you can cool them and they will become less active. Of course, you can overdo this a harm or kill them. Be sure not to place them in the freezer - it will kill them if left there too long. Subjecting the same butterfly too many times to the refrigerator is likely harmful as well. There are some alternatives depending on what you want to photograph. For example, I have taken good photos of the wing scales using dead butterflies (ones I found dead). In addition, you can find some species in their roosting locations (where they rest) if you learn these. On cool mornings or evenings they can be photographed with ease if they are roosting. Of course, it takes some time to photograph them at the magnification you are talking about. Wind and other factors can be irritating and the butterflies can awaken and begin to move once they begin to warm. Of course, this warming will happen when you take them out of a refrigerator as well unless you keep them in some type of cool environment. Again, I recommend you not subject more rare species to the refrigerator routine.