Pignut growth stages

Q: What are these growths on my pork hickory leaves? I think they are insects and they are chewing my leaves.

A: I appreciate you bringing in examples of the growths as this helped me identify the problem more easily. In reality, these growths are probably insect galls. Galls are formed when the female insect lays an egg in the leaf tissue and the plant then forms a protective shield around the egg. The egg then goes through its normal stage of growth from egg to larva then the pupae emerges from the gall as an adult. Generally, these galls cause few problems for the plant and in some cases, the galls feed beneficial insects. I believe the chewing you are seeing on the edges of the leaves is caused by a caterpillar such as the eastern tent caterpillar. Eastern tent caterpillars can be seen in our area in April – right now! Just poke holes in the webbing of the belly and the birds and wasps will take care of the caterpillars for you.

Where to find shagbark and pork hickory trees

The two species are often found together and each grows to about 90 feet, usually in mixed oak forests. In my area, hickory trees are common along the roads, so I often forage along back roads. They tend to have good results there, as they get a lot of sun exposure. According to the USDA plant profile, the shagbark hickory spans much of eastern North America. However, it is uncommon in northern New England and Canada. Pignut hickory ranges over most of the eastern United States, Texas, and Ontario.

Mature hickory shagbark tree before leaf out in spring

Euonymous caterpillar

Other we do he discovered in addition to the Euonymous Caterpillar. This clever insect lives on one species of tree and when the moth finds this tree, it makes full use of the unfortunate victim and covers it with eggs. These survive the winter to hatch now – especially after a hot dry spell into a whole web of thousands of caterpillars weaving a silk tent that now completely covers our Euonymous or Spindle tree.

Inside this tent, the caterpillars are safe from predators and bad weather and can store everything they need until they are ready for the next stage of their life as they metamorphose from caterpillar to flying moths. They will drop to the ground on long silk threads and breed for a few weeks, then fly away and lay their eggs on another Euonymous tree (hopefully) and ours should be able to recover.