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Thursday - May 17, 2012

From: Austin, TX
Region: Southwest
Topic: Butterfly Gardens, Pests, Vines
Title: Caterpillars eating passion vines from Austin
Answered by: Barbara Medford

QUESTION:

My question concerns Yellow passion flower, purple passion vine & butterflies. I have had my passion vines for 3-4 years, each spring they start growing beautifully, then in 1-2 days are almost completely stripped of leaves. I have found caterpillars eating them (makes sense this is their food supply) but after the caterpillars are done I see no further leaves until the following spring. And the process starts all over again. After 3 years I finally have seen 1 flower starting on my purple passion vine . By the next day something had chewed a hole in it. I don't want to deter the caterpillars; is there something I can do to help my plants recover after the caterpillars have dined?

ANSWER:

Okay, which comes first, the passionflower or the butterfly? Our observation of passionflowers in the wild or in somone's garden is that they grow rapidly and almost invasively, and even if the caterpillars ravage them, the next year the vines and flower are back, again.

Passiflora lutea (Yellow passion vine) is a major larval host to Julia, Mexican & Gulf fritillaries butterflies, Zebra & Crimson-patch longwing butterflies. It is shown on this USDA Plant Profile Map as being native to Travis County. Blooms May to September.

Passiflora incarnata (Purple passionflower) is a larval host to Gulf frittilaries, Variegated Frittilary, Banded Hairstreak and Red-Banded Hairstreak. According to this USDA Plant Profile, this plant tends to be native to counties to the east and south of Travis County. Blooms April to September.

Many of the webpages on individual larval host plants have pictures and a link to BAMONA (Butterflies and Moths of North America). You can click on this "Learn More..." link to BAMONA to see what other host plant there might be. There are pictures of the butterfly, the larva (caterpillar) and the chrysalis.

You probably already know that any insecticide will kill the larvae and reduce the chances of that butterfly recurring in your neighborhood. Both of the above flowers attract the butterflies, and the female then lays eggs, which develop into caterpillars.

There are other butterfly attracting and larval host plants native to this area, specifically members of the Asclepias (milkweed) genus. They tend to be a little weedy and maybe not so favored for their flowers as the passionflower, but the butterflies love to use them as nurseries:

Asclepias amplexicaulis (Clasping milkweed)

Asclepias asperula (Spider milkweed)

Asclepias asperula ssp. capricornu (Antelopehorns)

Asclepias incarnata (Swamp milkweed)

Asclepias oenotheroides (Zizotes milkweed)

Asclepias tuberosa (Butterflyweed)

Since the passionflowers are perennial, you might consider planting milkweeds in the same area to attract some of the butterflies laying eggs and thus the larvae. We have grown milkweeds and in spite of having many butterfly larvae on them, they have flourished and bloomed again. Then, when your passionflower is either eaten up, but the larvae are gone and the flowering is over or nearly so, you could trim it back pretty severely. Plants really need to reproduce themselves and they will hopefully bloom again to produce more seeds.

But, back to our initial question-do you want the passionflowers or the butterflies the most? You need to remember that Nature would probably not allow a species to completely destroy its larval host. You may not end up with as many leafy, blooming passionflowers, but you would still have both them and the butterflies.