Besides predators and parasites there are various pathogens which can affect caterpillars. These are described in detail in our course material (Lesson 5).
Firstly, bear in mind that in the wild a pair of adults only needs to produce two healthy adults to continue the species. When a male and female butterfly mate, and the female begins egg-laying, some of her progeny are destined to be food for other animal life. A female monarch can lay 300 or 400 eggs – one female was kept in captivity and laid over 1,000 – but so long as two make it to adulthood and reproduce, all is well.
In Nature pests (predators, parasites, pathogens etc) are there to control any living form, and are usually only a problem when a population of any species gets out of control. There are millions of biological interactions and processes occurring within a healthy community of plants and animals – both above and within the soil. Many of them go unnoticed and unappreciated. Biological diversity gives balance or stability in which pest outbreaks rarely result in significant damage.
Now pathogens (bacterium, virus, or other microorganism that can cause disease) are usually invisible (just like when we catch the flu – we can’t see the flu virus but know to stay away from anyone who has it. But what about the person who has it, doesn’t know they have it and isn’t showing any symptoms at that point?)
I have a friend in Florida who used to have an amazing webpage showing all the different symptoms of monarch (and other butterfly) diseases. Sadly they lost the page and she’s currently redoing it. I’ll share the interesting photos when she sends me the link.
The important thing to ask yourself is:
What percentage of my (insert name of species/stage) are suffering/dying from these symptoms.
If you are releasing 5-6 monarch butterflies every day, you’ve may well have something like 40-50 caterpillars or more in your habitat/butterfly house (or whatever). If two or three die, this is probably normal and nothing to worry about. If you are losing a large percentage every day, then you’ve got an epidemic and that’s where you need to do something about it.
Even before the experts knew we had Oe in New Zealand, I had an outbreak of it in my butterfly house. It was my own fault. I met up with some friends who lived nearby and they had the back of their light truck heaped up with swan plants. Off to the dump! I looked and there were countless caterpillars and eggs on the plants so I asked them if they’d leave them at my place. I hauled all these plants up two levels (yes!!! I lived three storeys above the road) and put them into my butterfly house. Then I went back down to the roadside and collected any caterpillars that had dropped off during the big haul.
I put the plants in a bucket of water and there were a mass of caterpillars on the plants. A week later and there was a certain smell in the butterfly house. Some caterpillars had pupated but the smell got worse. I now know that was from the disease/death and can recognise that smell now. It smells TROUBLE!!
Anyway, I had to ditch the whole lot of caterpillars and plants and spray everything with a bleach solution (10%). Didn’t have any more problems after that. I learned my lesson! Don’t put your caterpillars under stress.
I urge you to think about doing the Create Butterfly Habitat Course on line. It’s the last day today for the cheaper rate, the price goes up tomorrow, 1 April.
Butterfly Gardening/Habitat Course
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So, Jobele, what percentage of your caterpillars are dying mid-pupation? Is it every one, or the occasional one?
Report a pest
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