Each week, we pick a question that we get through our Master Gardeners hotline and write an article for the popular, online magazine Rural Intelligence. Below is this weeks article.
This attractive little bugger is the Lily Leaf Beetle. Native to Europe, it was first spotted in Boston in 1992 and has quickly spread to the rest of New England, all the way to southern New York.
Don’t let her good looks fool you. The Lily Leaf Beetle will defoliate and destroy a variety of lily (Lilium) species, (such as Asiatic, Oriental, Easter, Tiger and Turk’s Cap lilies) and right now is when they are coming out to party, mate and lay their eggs. (They are definitely not lady bugs! Lady bugs are actually very GOOD for your garden.) If you see them in your garden you need to take action.
Here’s what to do:
First of all, if you see these on a plant you are purchasing or if a frenemy is trying to give you one as a gift, politely decline. Same goes for you – don’t share plants that have the beetle or you could unintentionally spread the problem. The real damage from the Lily Leaf Beetle occurs in the larva stage after the eggs laid by adult beetles throughout the spring (right now) have hatched and come out hungry. Larvae of this beetle are beyond disgusting. They look like slugs with brownish bodies and black heads. If that weren’t repulsive enough, they secrete and carry their excrement on their backs to ward off predators. After they have fed for 16-24 days, larvae enter the soil to pupate. New adults emerge in 16-22 days and feed until fall when they head back into the soil and wait until spring to mate and start the process all over again.
If you do notice them in your home garden and have a concentrated planting (at left is an example of what can happen with them), the best first defense is to try and remove them by hand. First, place a white sheet of paper around your plant – the beetles are easily spooked and tend to fall off plants when touched. They almost always land on their backs, which are black, making them impossible to spot on the ground. Having a piece of paper there for them to land on makes them easy to spot. Monitor your plants every couple of days and remove any new beetles that appear. There’s hope for revival even at the state pictured here.
If you have a large planting and the problem is more wide-spread, you may want to consider a spray. You can use a pyerthroid insecticide or if you want to go a non-toxic, more earth friendly route, consider using a Neem spray and reapply every 4-5 days to get any eggs that may have hatched. You’ll want to continue this process through June to catch any late arrivals and prevent them from laying eggs.
When you do catch them, kill them. Put them in a jar or bucket of soapy water and that should do the trick.