looking for help on determining type of insect (thinking it's caterpillars) - Ask Extension
I have a shrub (small tree?) in my yard that I believe is a species of mock orange based on the leaves, bark and flowers. Most of the flowers appear ...
Knowledgebase
looking for help on determining type of insect (thinking it's caterpillars) #870719
Asked May 30, 2024, 10:01 AM EDT
I have a shrub (small tree?) in my yard that I believe is a species of mock orange based on the leaves, bark and flowers. Most of the flowers appear to have 4 petals but 1 flower has 5 petals. On Monday, May 20th, I noticed a bunch of very small translucent, white, round eggs on 1 of the leaves. I took some photos and counted them (using draw feature to add dots) and found there were 211 eggs. I noticed eggs kept disappearing and even witnessed what I think was a lacewing stealing 1. I decided to put them in a container and keep them in my sunroom, at which time, there were only 186 eggs. They hatched on May 25th. I think they are some sort of tiger moth caterpillar, more specifically Isabella tiger moth (woolly bear caterpillars) but am looking for help on identifying them. They have been eating the leaves from the supposed mock orange shrub. I have searched the internet and cannot find anything that shows it uses mock orange as a host plant but I do understand that some caterpillars are generalist eaters.
Baltimore County Maryland
Expert Response
We agree that the plant appears to be a Mockorange (Philadelphus), and some varieties of this shrub do mature quite large, especially if not regularly pruned. (Pruning is not required for plant health, just something many gardeners do if they prefer more compact plants.)
You've made some great observations, but unfortunately we can't ID the eggs or larvae with certainty, as there are too many moth species present in Maryland and many have indistinct traits at that stage of development. (Maryland Biodiversity Project, for instance, lists over 2,700 moth species in its database. There are many fewer butterflies than moths, and no local butterflies have this host plant or egg and caterpillar appearance, to our knowledge.)
You could try to continue rearing the caterpillar brood on the Mockorange foliage and see what matures...sometimes older larvae are unique enough to identify, but if not, the eventual adults will be another feature you can compare with the life cycle stages of local species. As you noted, a number of species are generalists and can utilize a wide range of unrelated host plants, so even though Mockorange is not native, that might not matter to some of our native (or non-native) moths.
We're aware of a Natural History Museum (from the UK) database of butterfly/moth host plants worldwide, but we don't know how extensive its data set is. Searching Philadelphus brings up a relatively small list of species (though it might be incomplete), including several present in the Nearctic (most of North America), so that might be a starting point, if it's helpful. Isabella Tiger Moth is not among them, but again, it might not be a comprehensive list.
Miri
You've made some great observations, but unfortunately we can't ID the eggs or larvae with certainty, as there are too many moth species present in Maryland and many have indistinct traits at that stage of development. (Maryland Biodiversity Project, for instance, lists over 2,700 moth species in its database. There are many fewer butterflies than moths, and no local butterflies have this host plant or egg and caterpillar appearance, to our knowledge.)
You could try to continue rearing the caterpillar brood on the Mockorange foliage and see what matures...sometimes older larvae are unique enough to identify, but if not, the eventual adults will be another feature you can compare with the life cycle stages of local species. As you noted, a number of species are generalists and can utilize a wide range of unrelated host plants, so even though Mockorange is not native, that might not matter to some of our native (or non-native) moths.
We're aware of a Natural History Museum (from the UK) database of butterfly/moth host plants worldwide, but we don't know how extensive its data set is. Searching Philadelphus brings up a relatively small list of species (though it might be incomplete), including several present in the Nearctic (most of North America), so that might be a starting point, if it's helpful. Isabella Tiger Moth is not among them, but again, it might not be a comprehensive list.
Miri
