Azalea sawfly larvae
On June 22, 2019, Sandy was visiting our neighbors across the road, and they told her that they had some kind of caterpillar infestation on their azaleas. They have two azalea bushes, a large one with yellow and white blossoms;
and a smaller one with pink blossoms:
The damage was most visible on the pink-blossomed azalea, with the leaves at the end of the stems chewed all the way down to the midrib. It took a few seconds to actually see the culprits, who are excellently camouflaged and tend to nestle down in the groove that they have just cut in the leaf edge.
While these superficially look like caterpillars, they are not going to be moths. If you look at the side view, you can see that they have more than five pairs of prolegs (moth caterpillars would have five or fewer pairs)
They also tended to wave their behinds in the air threateningly if they were disturbed.
These are traits typical of sawflies, which are a group of insects that are related to bees, ants, and wasps. Specifically, these would be Azalea Sawflies (no surprise there!), which are either Nematus lipovskyi, or Amauronematus azaleae.
While there are chemical pesticides that can be used for these sawflies, I asked the neighbor not to spray because my bees were currently visiting her azaleas. Instead, Rosie and I picked off as many of them as we could find by hand, which is actually the recommended way to get rid of them if there are only a few plants to deal with. Rosie squashed a lot of them on the spot, and I kept a bunch to bring home for further photography with the macro camera. Here is the seething mass that I carried home in my hand (we had probably around 30 of them, not counting the ones Rosie squashed in place)
Another sawfly trait is that the caterpillars have distinct little black eyes, which you don’t normally see in moth or butterfly caterpillars.
Once we were done taking pictures, Sam suggested that her chicks might like them (she has bantam chicks that, at the time, were only about a week old). So, I put them in the chicks’ box. They looked deeply suspicious of them until the bravest one came out, picked one up, and ate it. That must have been a signal, because then the other five chicks all came charging out and went nuts, completely devouring all the sawflies in a few seconds.
This obviously suggests that chickens are probably good for azalea sawfly control, especially since the larvae drop off to pupate in the soil, where scratch-feeders like chickens will find them easily.
Incidentally, the azaleas our neighbor has are derived from north american native plants, and are the deciduous azaleas that drop their leaves in the fall. These are distinct from the evergreen azaleas that were imported from Asia. The azalea sawflies only eat the deciduous azaleas, not the evergreen types.
Aside from traditional chemical sprays, picking them off by hand, and chickens, the other recommended ways to get rid of azalea sawflies are to knock them off with a hard water spray with a garden hose, or use insecticidal soaps. Insecticidal soaps work by a combination of drowning (the soap reduces surface tension, so that the caterpillars end up inhaling water into their breathing spiracles) and washing off the protective waxy cuticle that normally keeps them from drying up. The nice feature of insecticidal soaps is that they don’t leave a lingering toxic residue. There are commercial insecticidal soaps, or you can apparently make them yourself.
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Sawfly larvae are also a favorite of bluebirds and I bet a chickadee would love to take a mouthful home to her young.
Sweet, delicious sawfly larvae!