The End of the Butterfly Irruptions?

There have been irruptions–rapid increases in the numbers–of several butterfly species this season.

Will irruptions of the natural predators of those butterflies cause a decrease in the numbers?  This is one of those natural predators.  This is a tachnid fly–I don’t know the species.   The larva of these flies become internal parasites of other insects, most commonly caterpillars.  So will there be a rapid increase in the numbers of these natural enemies of butterflies, and the will there be a decrease in butterfly numbers later this year?  Possibly.  That’s often how nature works.

But I kind of hope it doesn’t happen that way.


About the roused bear

Nature photographer from central Iowa.
This entry was posted in Biological diversity, diptera, insects and tagged , , , . Bookmark the permalink.

1 Response to The End of the Butterfly Irruptions?

  1. John Pearson says:

    Hi Harlan, I think it will work out the other way. Irruptions have the effect of suddenly outnumbering predators so that there are more survivors than in a normal year when predator-to-prey ratios are higher. Maybe it works that way for parasites too?

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