Good Weeds?

Posted by & filed under Tom Houser Blog.

One Man’s Weed is Another Caterpillar’s Dinner……

Last week, I was hand weeding the Norfolk Botanical Garden Native Plant Display Bed (next to the Butterfly House) when I spotted a caterpillar, in one of the plants I was getting ready to yank.  The day before, I had seen several butterflies in that same area where they seemed in search of a  host food to lay their eggs. I knew they were either American Ladies or Painted Ladies, but I didn’t take the time to make a positive identification.

So….. I did what I usually do in a situation like this – I broke out my phone and starting looking up some information.  Within 5 minutes, I had a solid ID on the caterpillar (American Lady  “Vanessa virginiensis”).  I then looked up host food information for this species and quickly identified the plant they had laid their eggs as a Cudweed.  After more research and consulting with my boss, I believe that more than likely, it’s the Purple Cudweed (Gamochaeta purpurea), but I also think I have some Pennsylvania Cudweed (Gamochaeta pennsylvanica) in the bed.  Any plant in the Gamochaeta genus will serve as host food for the American Lady.

I am always incredibly excited when I find a new butterfly/host plant relationship. I’ve been gardening for butterflies for over ten years, but this was a new discovery for me – and another example of why you might want to be a little more observant when you’re working in your garden. I quickly shifted from looking at the cudweed as an undesirable nuisance that should be removed to looking at it as vital host food for one of our iconic native butterflies – and therefore as something to be protected, not pulled!

Some plants with caterpillar activity were so easy to spot – their species is one of many that build “larval nests” to protect themselves from predators while they feed on the plant.  They actually use silk to pull leaves from the plant into a tent of sorts, one of natures amazing adaptations!  Luckily, I had my camera with me and was able to take some photos.

Just two days later, I was working in one of my garden beds at home, looking to plant a few zinnias from seed. I was considering pulling some violets out to make room for the zinnia seeds, when I looked down, and noticed a Variegated Fritillary caterpillar (Euptoieta claudia) munching on the leaves.  This was one butterfly/host plant relationship I was aware of, but had never observed in my yard. I’ve always allowed violets to grow in my beds for this reason. They also block out other weeds  far worse than they are –  I now feel rewarded!

I’ve been growing lance leaf plantain (considered as a terrible lawn weed by most homeowners) in one of my beds for several years now in the hopes a Buckeye butterfly will lay its eggs on it – all of this other activity, has me thinking that this will be the year!

I hope you will now be on the lookout for caterpillar activity in your yard. I know every butterfly gardener is always looking for what they call “magnet” plants, with stunning color and promise of nectar, that attract these beautiful creatures. It would be a shame to remove a host plant the butterflies depend on for reproduction, just because it’s a weed! Not sure if the plant you are about to remove is a needed host plant, do some quick research….your butterfly friends would really appreciate it!


Caption #1   The American Lady caterpillar that caught my eye!

American Lady Caterpillar











Caption #2   A purple cudweed – a very inconspicuous host plant.

purple cudweed













Caption #3  Larval nest built by a caterpillar for protection from predators.

Laval nest



















Caption #4  Adult American Lady on purple coneflower.

Adult American Lady













Caption #5  Variegated Fritillary caterpillar eating violet in my yard.

Variegated Fritillary Caterpillar













Caption #6  Adult Variegated Fritillary

Adult Fritillary