Social distancing regulations may be preventing some individuals from conducting research, but gall hunting has continued in full force. These outings have mainly been a solo activity — observing and collecting galls on oaks in Centre County. Leading to amass approximately 400 galls(!), all of which are being reared from a makeshift lab space in my living room apartment. This isn’t the ideal set up for observations, but once we went into lockdown, I moved all of the galls I was monitoring into my apartment to reduce possible COVID-19 exposure. This summer, I’ve bumped into a few particularly interesting galls on red oaks that I’d like to highlight.

The first being Amphibolips nubilipennis, commonly known as ‘Translucent Oak Gall Wasp’. This gall earned ‘Observation of the Day’ on iNaturalist back in June! Although many commented on its bubblegum appearance, its firmness and heftiness reminded me more of a bouncy ball. However, not all translucent galls belonging to this species share that bright pink coloration. A different A. nubilipennis gall that I was able to rear was actually much smaller and clear and had a parasitoid wasp emerge instead. This clearly illustrates how the salivary secretions from A. nubilipennis are what signals the gall to grow bigger and pinker.

Another interesting observation I made also occurred back in June. While out collecting, I noticed a spongy oak apple gall, Amphibolips confluenta, that contained two exit holes, which seemed unusual. The first exit hole was likely from a gall wasp at only 1mm in diameter, while the second one was considerably bigger at 7 mm. Since the presence of a gall wasp size exit hole meant I likely couldn’t rear a gall wasp from the gall, I decided it was worth opening it up to check out why it had such an odd, larger opening. I discovered that a leafcutter bee had co-opted the inside of the gall to make its nest. It appears like the bee excavated the inner spongy structure in order to lay her eggs. I’m currently trying to rear the larvae so we can identify the species of leafcutter bee and compare this nest to its normal nesting material since they generally use straight structures for their nest. In the meantime, we are arranging to get the gall x-rayed so we can see the inner modifications of the gall without disturbing the larvae.

Last but not least, our most recent exciting observation was of the asexual generation of Callirhytis quercusoperator. While looking for pip galls under the red oaks in front of the Frost Museum, I noticed a bunch concentrated on an ant colony. Pip galls resemble small seeds that grow between the acorn and the cap and easily detach when the acorn falls from the tree. After some inspection, we noticed that it was actually a combination of whole and empty gall shells. We can only speculate that the ants collected them and are using everything inside of the gall for nutrition — plant tissue and wasps alike — since we didn’t find any discarded gall wasp larvae near the nests! It was definitely surprising to see this type of gall predation since ants are never listed among common gall wasp predators. On the contrary, they are actually known for having a mutualistic relationship with nectar‐secreting galls.

On a final note, I was recently invited to talk about gall wasps in the Arthro-pod podcast. Check it out!