If you have trouble keeping track of your kids, imagine having 50 of them at once! That’s how many offspring the dead-leaf mantids in the Indonesian Rain Forest produce in a single batch. These big bugs are a type of praying mantis perfectly camouflaged to look like dead leaves.
Zoo keepers are working on breeding a self-sustaining population of this species, so the 50 tiny mantids were a welcome addition.
Zoo keeper Dave Messmann explains why it’s important for the zoo to breed and support its own population of dead-leaf mantids, as opposed to relying on outside sources. “We want to sustain our population so we don’t have to have new insects shipped to us,” he said. “If one of our populations crashes, there is no guarantee that another zoo is still exhibiting this species. Even if they do have some, they may not have any surplus animals to send us.”
Dead-leaf mantids can reproduce in two ways. One is fertilization, when a male mantid approaches a female in the traditional mating ritual, resulting in fertilized eggs. As with other praying mantis species, the female is larger than the male and may become aggressive shortly after mating. Females can also reproduce via the asexual method of parthenogenesis. This happens when the female lays unfertilized eggs that hatch into viable young. Parthenogenesis typically results in female offspring since there is no genetic component from a male without fertilization.
Whether fertilization or parthenogenesis occurs, the next step is the same: the female produces an egg case called an “ootheca” (see photo on left) in which eggs are deposited. In the case of fertilization, the female makes the ootheca 4-6 weeks after mating. The material for the ootheca is excreted from her abdomen like a ribbon and formed into a case that will protect her eggs. She adheres the ootheca to the wall of the aquarium she lives in.
The zoo currently has one adult male mantid and keepers believe that the 50 new babies resulted from fertilized eggs.
Babies emerge from the ootheca after five weeks and look like miniature adults. They go through six instars (phases) before reaching full maturity. The young, or “nymphs”, double in size during each instar, then shed their skin before doubling in size again. The six instar phases take about 3-4 months. Dead-leaf mantids live about one year.
Dead-leaf mantids eat pinhead crickets and certain types of vegetation but will sometimes prey on each other. They are native to Southeast Asia.
Zoo babies are sponsored by Lutheran Children’s Hospital. Click on the photos to enlarge: