Friday, July 10, 2009
Why hasn't my swallowtail emerged from its chrysalis?
"Why hasn't my swallowtail butterfly emerged from its chrysalis (pupa - cocoon)?
This question is difficult to answer as it is asked. First, there are a few questions that need to be answered.
1. What species of butterfly?
2. How long has it been since it pupated?
3. Where has it been held since it pupated? (Indoors, garage, etc)
4. What type of humidity is near the chrysalis? (living plant, spraying it with water, etc)
5. The chrysalis is in how many hours of light?
6. Does the segmented abdomen move it you apply GENTLE pressure to the side of the abdomen?
7. If so, does the abdomen move back after you apply pressure?
8. Does the chrysalis feel like it weighs normal or is it super light?
9. Is there a tiny hole in the chrysalis? Have you seen small 'gnats' near it?
So ... why these questions? Let's take them one by one.
1. Generally, it helps us understand more about the butterfly if we know which species we are discussing.
2. If it pupated last week, it could simply be taking a while. Swallowtails are not known for their emergence to be as predictable as other species of butterflies. If it has been a month or more, we need to look further into the situation.
3. If it has been in an air conditioned or heated building or in an area without humidity, it may have dehydrated. If it is in direct sun or a in a bright window, it may become LITERALLY cooked due to the heat from direct sun, especially through glass. (See next answer.)
4. Assuming it is where it could become dehydrated, we need to know if a source of humidity is near the chrysalis. If you has a living plant with the chrysalis, the plant will probably add the needed humidity to the air. If you are spraying it with water two times a day, it should not dehydrate. If a wet sponge or other source of evaporating water is with the chrysalis, it should not be dehydrated.
5. If a chrysalis is in less than 14 hours of light, it may still be in diapause. Swallowtail butterflies spend the winter as a chrysalis and can stay a chrysalis for 9 months and more if the day length where the chrysalis is located isn't 14 hours or more.
DO NOT put it in direct sun. It should be in bright light but NEVER direct sun. It can be kept on a table NEAR a window IF the table receives 14 hours or more light. Artificial light is adequate. Our farm's swallowtail pupae are never placed in sunlight but are kept in a lab with ONLY fluorescent lighting. NOTE: diapause is determined by the length of daylight or night, NOT by temperature.
6. A dead swallowtail chrysalis' abdomen will be frozen in place and cannot be moved when GENTLE pressure is applied at the jointed part of the chrysalis. If it moves, the tissue between the segments should be light in color. (See #9)
7. If it does move, it should move back to it's normal position after pressure is released. (See #9)
8. If the chrysalis is dehydrated, it will feel as light as a feather or cotton ball. The butterfly inside will be totally dehydrated.
9. Chalcid wasps are parasitoids. They lay eggs inside a soft chrysalis and eat the chrysalis from the inside out. If a chrysalis is infected with chalcid wasps that have not yet emerged, the tissue between the abdominal segments will lose the normal light color and will become dark.
Mature chalcid wasps eat a tiny hole in the chrysalis and emerge. A tiny hole in a chrysalis is a sign that the maturing butterfly inside was food for maturing chalcid wasps and they have emerged.
If a chrysalis is infected with chalcid wasps, it is NOT a butterfly chrysalis any longer. It is a shell for chalcid wasp larvae or pupae.
Side note: A butterfly does not make a cocoon. Some moths make cocoons. Learn more about cocoons here.
If the above doesn't help with your question about your chrysalis, please feel free to write to firstname.lastname@example.org with your questions about your chrysalis or any other butterfly question.