Friday, December 18, 2009

Why didn't my butterfly eggs hatch?

We're often asked why someone's butterfly eggs that they brought in from their garden didn't hatch.  The bottom line is, in most circumstances, we don't know for sure!

[First photo; healthy Monarch egg]

But we do know several reasons why they perhaps didn't hatch. 

1.  The eggs were infertile.  Yes, females that do not pair will often still lay eggs.  After a few days, the eggs start to collapse on themselves, losing their plumpness and beauty.

[Second photo; infertile eggs after several days]

2.  Trichogramma wasps. These rascals are tiny!  They lay eggs in freshly laid butterfly eggs and the wasp larvae eat the inside of the egg.  Instead of a caterpillar, many miniature wasps emerge.

[Third photo; trichogramma wasp and Brazilian Skipper butterfly egg]

[Fourth photo; trichogramma wasps leaving a Giant Swallowtail buttterfly egg]

3.  Excessive Heat.  The eggs were in a spot that became too hot.  They should never be kept in a window or car.  Just like chocolate melts, eggs will cook. 

4.  Insect spray.  Eggs in a room that has had insect spray in the room can die.  NEVER use insecticide in the same room as butterfly or moth eggs, caterpillars, chrysalises, or adults.

[Fifth photo; Hatching Monarch caterpillar from a Monarch egg]

These are just four basic reasons why perhaps someone's eggs didn't hatch. 

There are several reasons why you may find your butterfly eggs empty or totally missing.  We'll cover those topics in another post.