“What are these caterpillars collected in Western North Carolina on pagoda dogwood in mid August?” asks this reader of the creatures in the photograph below. The critters, as we can see, are black and yellow in color, with clear segments divided by gray lines and multiple legs on the underside of their bodies.
Firstly, we want to thank our reader for the excellent photograph; the resolution, lighting and colors are great and this greatly helps us in identifying the creatures. Secondly, we want to note that although we are tempted to say that our reader is right in calling these caterpillars, these critters are not caterpillars at all, but in fact dogwood sawfly larvae! The sawfly is a type of fly often mistaken as a wasp. The dogwood sawfly just happens to be a species of sawfly whose larvae feed specifically on the leaves of dogwood plants, such as our reader’s pagoda dogwood. In fact, the adult sawfly also lays her eggs on the underside of the same leaves, conveniently leaving her offspring right at their food source.
Dogwood sawfly larvae tend to stick in groups (as seen in our reader’s photograph), similar to the fall armyworm, and will likewise feed on the plants they are named after in groups. Because of this, they are very efficient at eating through the leaves of many plants in a short amount of time. That being said, The Scott Arboretum of Swarthmore College’s page on dogwood sawfly larvae states that the damage caused by these creatures is not long-term as they feed most ravenously from mid-summer to autumn before stopping to find somewhere to overwinter. On a different, but related note, we find it curious that when they overwinter, dogwood sawfly larvae are not actually pupating. They are in their last molt (stage) as a caterpillar, but they do not enter pupation until after hibernation in early spring.
Moving on, should our reader want to control the population of dogwood sawfly larvae, the same source also suggests that the best method of control is handpicking the larvae and putting them in soapy water to kill them. Now, unless the circumstance is dire and calls for it, we do not condone killing creatures. For this reason, we would rather suggest hand picking them (use garden gloves to prevent unexpected allergic reactions!) and moving them to another location. Of course, their diet being very specific, it might be that putting them in any random environment may end up killing them in the long run anyway. We do not ask that our reader goes hunting for naturally occurring dogwood plants in order to find these larvae a new home, but if possible, we suggest leaving them in a forest, where the biodiversity will statistically raise the chances of there being dogwood plants for the larvae to feed on. That said, our reader may not even be considering controlling the population, as he only asked for their identification. But in the case that he does want to limit their growth, or get rid of them entirely, we hope that this information helps.
In conclusion, the ‘caterpillars’ our reader found on his pagoda dogwood are actually dogwood sawfly larvae! We hope this brief look at these larvae proves helpful to our reader, and that his plants may prosper despite the presence of these little critters. Should our reader want any more information on dogwood sawfly larvae, he is welcome to contact us again or leave a comment below!