Raising Fireflies?!

As I’ve described previously in this blog, it’s generally proven difficult to raise U.S. fireflies. Once you’ve gotten the eggs to hatch, the next problem is getting the larvae to eat, grow, and survive. It sounds simple, but it takes young fireflies up to 2 years to develop. As their size increases, they need to shed their old exoskeleton & grow a new one. Each of these molting cycles is called an instar, and fireflies need to go through ~11 larval instars before they’re finally ready to metamorphose into the adults we’re familiar with.

So I’m really excited to report that so far I’ve had pretty good luck this year!

I’ve been caring for  ~20 very active Lucidota larvae that hatched from eggs. Now 2 weeks old,  they’re shown below climbing on a bit of earthworm poop. Because they’re still small, every few days I feed them cut-up pieces of earthworms (yuck). After enjoying a gluttonous feast last week, many have molted into a new instar.

And my two remaining Ellychnia larvae are now 10 weeks old, and I’ve taken them on the road all summer. When I give firefly talks, I bring these firefly babies along and they’ve been quite a hit. And they’ve grown huge! A few weeks ago you needed a magnifying glass to see them, but  now they’re the size of my fingernail. Working together, two can take down an entire earthworm.

Following a hefty meal, my 10-week old Ellychnia larva became lethargic, and then yesterday it molted! The one-day-post-molt larva is on the left (photographed under red light to minimize disturbance), and the shed exoskeleton is on the right (scale in mm).

Update September 1: I’m very sad to report that the last (of two) surviving Ellychnia larva died today of unknown causes. It was 3 months old. Just yesterday, it  had been happily feeding on an earthworm. Is it possible that it died from gluttony? Before its natural burial I took two post-death photos (mm scale).