The great outdoors can produce baffling mysteries. MV Times Wild Side columnist Matt Pelikan tries his best to solve them. Got a question for the Wild Side? Send it to firstname.lastname@example.org.
What is this creature? It was on plants outside my office… I’m not sure what the bush is so I took a picture of its growing berries in case that helps… Beach plums?
The Pelikan Brief:
That is a seven-spotted Ladybug on beach plum!
The rest of the answer:
These colorful but homely creatures are the larvae, or immature stage, of a ladybug. As most gardeners are aware, ladybugs are highly beneficial insects (at least from the human perspective) because both adults and larvae eat a wide range of insects that are harmful to plants. They specialize in preying on soft-bodied insects such as aphids, scale insects, and mites, which suck vital juices from plants and can also carry disease. Most ladybugs pass through four distinct larval stages as they develop, before morphing into an adult, and the energy source that powers all that growing and molting is the caloric content of a ladybug’s prey.
There are somewhere around 500 species of ladybugs in North America and, to make a rough guess, perhaps 20 species on Martha’s Vineyard. These particular larvae appear to be those of the seven-spotted ladybug, which is a Eurasian species that has been introduced widely in the U.S. to help control agricultural pests. It is now widely established — so widely, in fact, that it may be out-competing many of our native ladybugs, such as the two-spotted ladybug that is the official state insect of Massachusetts. (I bet you didn’t even know we had a state insect!)
Many, perhaps most, ladybug species are mildly toxic, producing chemicals that give them a foul smell and taste. The bold, distinctive patterns these beetles show — black spots on a red or orange background, or in some cases red spots on black — serve to warn away would-be predators that have had first-hand experience trying to eat a ladybug.
The plant the larvae are on happens to be a beach plum, and this is not just coincidence. Beach plum, like its close relatives the shadbushes and wild cherries, is notorious for attracting sucking and leaf-eating insects of a wide variety. The plants of this family, in other words, furnish a prey-rich environment for ladybugs, and as a result are good places to look for these most excellent beetles.