Dogwood Sawfly – Macremphytus tarsatus
Common Name: Dogwood Sawfly
Latin Name: Macremphytus tarsatus
Appearance:
Adult sawflies emerge in early spring and lay their eggs on the undersides of leaves. The first-stage larvae are small, yellow, and transparent when the eggs hatch in the middle of the summer.
They acquire a white waxy covering as they develop and molt.
They often curl up and cling to the underside of leaves throughout the day. They are frequently highly sociable, gathering in groups of a dozen or more on a single leaf.
Though unattractive, their vast numbers can result in significant defoliation that often won’t harm the plant because it occurs late in the growing season. They often cease eating after their last molt and look for a safe place to spend the winter. They will pupate in the early spring and then emerge as adults.
Host plant:
The dogwood sawfly like Dogwood (Cornus spp.), Gray Dogwood (Cornus racemosa) are appear to have no other hosts save various dogwood species.
Damages caused by Dogwood Sawfly:
Sawfly larvae’s chewing mouthparts eat holes in the leaves. Some sawfly species leave behind windowpaning, which is very distinctive eating damage. They mostly consume the leaf’s green portion, leaving a thin coating of transparent leaf tissue behind. Older damage turns brown and occasionally resembles a disease lesion.
Life history and Habits:
There is one generation every year. The dogwood sawfly’s larvae spend the winter in rotting wood and occasionally weak structural timber. The soft wood in this creates an overwintering “cell.” Pupation occurs in the spring, and adults often don’t emerge until sometime between late May and July. On the underside of the leaves, clusters of more than 100 eggs are placed. The larvae eat gregariously after hatching, first skeletonizing leaves. Except for the midvein, the caterpillars can consume the entire leaf as they grow. Larval appearance varies so much between instars that it’s possible to confuse them with different species. Early larvae are invisible and yellow, but as they mature, the caterpillars have black dots (over yellow) and start to get covered in something like white powder. Larvae can resemble bird droppings, as can their lost skins. Larvae that have reached adulthood start roving in search of a good place to spend the winter. The best material for this is decayed wood lying on the ground.
