BUGarium Beetle-Mania

July 1, 2020 - The BUGarium may be temporarily closed, but behind the scenes, it’s beetle-mania.

Goliath Grubs

The BUGarium’s goliath beetles are finally growing to full size, a feat that BUGarium Curator Jason Schaller says few people on Earth have achieved. 

“Not just one or two, but 19 out of 27 male grubs (70 percent) exceeded 80 grams, which is the weight of two naked mole rats,” Schaller says. “Most breeders only get a handful to this size.”  He adds that this is the first time the BUGarium has gotten this species to sizes comparable to their wild counterparts. (Grubs are worm-like juveniles, also known as larvae.) 
 
A large male Goliath grub recently weighed in at more than 100 grams—that’s nearly twice the weight of his parents and about the weight of 20 nickels! 

“This big boy hatched from an egg in mid-August 2019 and took seven months to reach his full size,” Schaller says. A total of 75 eggs were laid last August-October; 48 survived to the pupa stage (where the grub turns into an adult). “This batch was still largely experimental so the survival rate isn’t ideal,” Schaller says. “However, we are eagerly awaiting our first big adult males, which are due in August.

The newest batch (hatched in April) is the BUGarium’s first using a new streamlined procedure. These new grubs are already growing much faster than the previous batch with hardly any losses, according to Schaller.

"Goliath beetles are considered a difficult and labor-intensive species to grow due to their predatory grubs and precise living conditions,” he says. “We’ve spent four years developing new techniques with major differences from the usual methods. But we’re not ready to reveal our secrets just yet.”

Herculean Hercules Grubs

But these Goliaths aren’t the only great grubs at the BUGarium. 

In late February, the BUGarium welcomed 24 Hercules beetle hatchlings. Seventeen of these little grubs survived and continue to grow. This is considered a great survival rate for this species. Staff prepared a home made rotting oak compost for the little ones to burrow into and feed on.

Some of these “baby” Hercules grubs are already “huge,” according to Schaller, and are half way to reaching full size after only 4 months.

“If all goes well, some will be over 100 grams by winter,” Schaller says. “At this point they will become a pupa, and then an adult—the full metamorphosis takes two to three months.”