Ladybug: Species of the Week

This is part of an ongoing series: Species of the Week.

They may be common and caricatured, but ladybugs (or as some scientists prefer, lady beetles) still give me a thrill.

Mating ladybugs

Because I’m a kitchen gardener, I’m especially excited to see ladybug sex. I found these two Coccinella septempunctata going at it in my herb bed last weekend.  I tore off my gloves and ran inside for the camera, thinking they’d finish and fly away soon.  I later learned there was no hurry.  Ladybugs can enjoy themselves like this for up to two hours.  I could have finished weeding and enjoyed a cup of coffee before bothering to snap a photo. Perhaps I should write Isabella Rossellini and urge her to cover ladybugs in one of her Green Porno Flicks.  Just imagine the costume, set and performance possibilities.

The herb bed where I found these two is where I once grew hops to arch over the breezeway between our house and garage.  Two years ago, when I taught social studies at an independent high school, my colleague brought his Botany students to learn about the possibilities for organic self-sufficiency in an urban yard.  Many students admired the hops, which were just beginning to display their buds.

Several days after the visit, I noticed thousands of aphids sucking the life out of the leaves.  Hoping for some predators to arrive, I tried not to worry.  But the infestation was bad enough, I almost considered trying organic soap spray.  I’m glad I didn’t.

Within days, I spotted the first ladybug larvae on the leaves.  I examined the undersides of leaves and saw thousands of small yellow eggs.  Those soon hatched into more larvae, very hungry larvae.  I put a few of them in a jar and took them to school  I showed them to the seniors who had recently visited and asked them what they were.   Not a single student knew them as ladybug larvae.  Most assumed that such a frightful looking critter would have to be a pest.  And that was my point.  Many gardeners who don’t know their insects would not associate these monsters with ladybugs.  They might drive to their local gardener center, buy the most lethal pesticide on the shelf, and exterminate every one of these garden allies.

Ladybug larvae

It pays for a gardener to learn to identify insects at all stages.  Each of these larvae eats 350-400 aphids during the two weeks before it attaches itself to a leaf and pupates.  An adult can eat 75 a day.  Within several weeks, the aphids on my hops had disappeared.  In fact, the late hatching ladybug larvae may have run out too soon.  They moved onto neighboring plants to seek out more juicy leaf-suckers.  I’m pretty sure some starved to death.

What I’ve learned from this is that beneficial insects flourish when we leave some food for them.  This is a tricky business for gardeners or farmers.  It was easy enough to watch the natural cycle on my hop leaves, knowing the hop heads themselves would be fine for a fall harvest.  It’s not so easy to watch aphids move into the heads of broccoli or cauliflower.  The damage is often done before ladybugs can take care of the problem, and the result is unpalatable.   So what would I do?  Go ahead and discourage or kill aphids on my broccoli with a blast of hose water or some pepper or soap spray but let them feast away on my hops and roses.  Unless my neighbors have chemically executed every insect for miles around, the ladybugs will show up soon enough, enjoy the feast and create the next generation.  Click here for more ideas on how to control pests while also supporting their natural predators.

I was surprised to learn that most ladybugs found in gardens in North America, including Coccinella septempunctata,  have been introduced from Europe. Any ordered from a beneficial insect supplier will also be non-native.  With their voracious appetites and some tendencies towards cannibalism, these beloved and helpful “invasives” may be implicated in the decline of native species, such as the two and seven spotted ladybugs, in most regions of North America. Cornell University has launched a project to document “the lost ladybugs.”   Their website had loads of information, including a field guide you can download to distinguish the various species.  They invite people from all over North America to help them identify and photograph ladybugs, especially ones suspected to be native.