Thursday, July 31, 2008

Feeding The Bugs

From Paul

spicebush swallowtail larva

Feeding the bugs

As much as it seems to run counter to what gardeners normally want, I like to feed certain bugs. Caterpillars, to be more specific.

As a kid, I spent many hours watching Monarch caterpillars eating their way through the leaves of the common milkweed (Asclepias syriacus). For some reason, I came to believe that was the only milkweed they fed upon. So, I was very happily surprised a few years ago to find many of my Asclepias incarnata (swamp milkweed) cultivars ('Ice Ballet', 'Cinderella', and 'Soulmate'- all various shades of pink) serving as host-plants to around a dozen Danaus plexippus (the latin moniker for Monarch butterflies) larvae.

early instar of spicebush swallowtail larva

Other garden-plant/butterfly relationships are quite common, although not all are exactly desirable. The larvae of the cabbage white (Pieris rapae) may be unwelcome to the grower of any of the mustard family (which includes cabbages, lettuces, turnips, broccoli, etc.). Still, it feels like there's a certain magic going on when one stirs up and walks through a fluttering cloud of dozens of them.
In my own garden, I allow the caterpillars of black swallowtails (Papilio polyxenes) free rein to munch my bronze fennels. This year, in the hopes of watching the metamorphosis from larvae to butterfly, we built a "cage" to hold larvae and their food. I may have to supplement the fennel with other plants in the parsley family (dill, carrots, Queen Anne's lace, etc.). As exciting as it is to watch this development, I got even more excited earlier this week when I discovered caterpillars of the spicebush swallowtail (Papilio troilus).

I've had a spicebush for several years now (there's one at the CGC, too!), and have also been aware that it was a larval food plant, but apparently missed seeing the caterpillars before. Now that I know they've "found" the plant, I feel like the plant has yet another season of interest (although rather a subtle one)!

The CGC has many plants that serve as both larval food host and nectar plants for adults (butterflies). Stop by and take a closer look to see who is nibbling on what!

black swallowtail larva

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