Massive Mediterranean Katydid Adult Eclosions

This whole week we have been having a huge wave of Mediterranean Katydids (Phaneroptera nana) eclosing into adult and expect many more to come in the following week, too. It's time to figure out how to breed them!

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When we started catching Mediterranean Katydids (Phaneroptera nana) around the end of May and into June, we always caught them in relatively large numbers since they live in aggregations. That being said, most of the katydids we collected in a particular region were usually of the same age since the environmental factors are the same and would have triggered the diapausing eggs to hatch at around the same time in the spring. In fact, a lot of them were probably siblings since this species likes to lay its eggs in clusters, in big rows that look like shingles. 

The oldest and by far the largest of these aggregations that we stepped upon was located on the passionflower (Passiflora) and bramble (Rubus ursinus) down at the Ohlone Greenway at Lincoln Ave. Around 6/17, we caught a total of 50+ katydids there, practically all either mature fourth instars or newly molted fifth instar. Now, its been just over a month since then, and virtually all of them are mature sixth instars. That's why, right now we are having a huge wave of same-aged katydids molting from sixth instar into adult. If you have been keeping track of our adult molt logs on the rearing notes, you'll know that we have had katydids molting every single day since 7/15. And as I write this, there are over ten other sixth instar katydids with super thick wing buds just ready to pop any day now. 

However, we have never gotten either of katydid species -- Mediterranean Katydids or Mexican Bush Katydids (Scudderia mexicana) -- to lay eggs in captivity. But that was largely due to the fact that we simply didn't wait long enough for it to happen, and probably not because we were doing anything wrong; usually we would just release the adults soon after they molted. In 2014, one of our biggest year for katydids, was the first time we ever reared Mediterranean Katydids to adulthood and we even got them to mate in captivity, but eventually let them go as well before they even had a chance to lay. This year we are determined to get them to lay some eggs so we don't have to work so hard next spring to find them to rear again! We've already set up an outdoor enclosure with a live plant in it to mimic more natural conditions, give the adults some more space, and hope that they get the cues to mate. After all, it shouldn't be too difficult for this first step since the last time we got them to mate, we simply put them in a tiny glass aquarium tank outside with a few dying bean plants inside -- the conditions of which were much worse than the enclosure we are using now. 

One the other hand, we are trying to develop some techniques to enhance the mating process. These katydids, like most Orthoptera, have quite complicated courtship and mating processes and either sex can be quite picky of the other in certain situations. One known phenomenon is the "gift" that the male katydid offers the female during mating  (via ejaculation, of course!), called the spermatophoryx. Not only does the male hand over his genes through the spermatophore, but also gives a very nutritious meal to help the female out (both are accepted orally, through eating it spermatophoryx). The exact benefit of such gifts varies from species to species and is not especially well documented, but it may serve to increase the females lifespan, allow her to lay a greater number eggs, increase the fecundity of the female, or result in stronger offspring when they hatch. Whatever the case, the female will often judge the male on his gift. So what makes a good gift then? Well, probably protein. The spermatophoryx is composed of some percent protein (varies depending on species), and this protein can only come from a good diet. Therefore, in order to ensure better mating success, we are thinking of supplementing the katydids with things like egg whites or fish food. 

Actually, we have already tried feeding them dead crickets and fruitflies in the past as an attempt to supplement their diet and deter cannibalism, but that would be difficult in the new outdoor enclosure since they would dry up into crisps in the sun instantly. Another method would be to feed flowers and pollen, the most proteinous part of most plants, which we used as well, but in the new enclosure the poor Blue Morning Glory (Ipomoea acuminata) is so small it only has two or three flowers every couple days that only last a day after blooming.

It often surprises people when they hear this, but most katydids don't like eating leaves that much just like most humans wouldn't like to be eating only vegetables all day long! Some actually specialize on flowers, pollen, fruit, or even nectar, while others are strictly carnivorous. Most all of them are opportunistic feeders that will scavenge for dead (or simply non-moving) arthropods to eat and like to "breakfast" on small eggs. Hence, the cannibalism issues we have been facing as of late. Phaneropterans (subfamily Phaneropterine) such as the Mediterranean Katydids and the Mexican Bush Katydids are already considered one of the most vegetarian katydids and can be raised from egg to adult on a leaf diet since that is how we've raised them in past years, but we doubt that would be optimal for overall health. This time we were smarter and more informed, of course. Right now, we are just doing our best to provide a natural habitat, an adequate diet, and give them enough time to reward us with some eggs. 

- Brian