Pipevines Are Ready for Pipevines!

The California pipevines (Aristolochia californica) have begun to grow new shoots and flowers, meaning there should be pipevine swallowtail (Battus philenor hirsuta) eggs on them soon.

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Like most other deciduous plants in our area, the California pipevines up in the hills are beginning to regrow their leaves and flowers as the weather warms. This plant is the sole host of the northern California pipevine swallowtail subspecies, Battus philenor hirsuta, and thus its regrowth is soon followed by the flight of these swallowtails which will lay large egg clusters on the growing shoots of the vine. It is very important that the vine be in a growing state because the butterflies refuse to oviposit on mature leaves, and the young larvae have trouble eating them. In fact, this is one of the prime reasons (the other being diapause) why the numbers of the butterfly decline in late summer when most pipevines cease growth, since the females have no where to lay their eggs on. Thus, spring time is the absolute best time to look for these eggs, as the butterflies will not only have a large flight due to all previous year generations breaking out of diapause, but because the pipevines are in the prime of their growth. Many of the pipevines right now are already covered in leaf buds and new vine shoots, while some are still covered in large masses of pipe-shaped flowers. Once these flowers fall off, those vines will also begin putting on vigorous  vegetative growth as well. If the pipevine swallowtails were already in flight now, we're almost certain that these growing shoots would be clobbered with bright orange-red eggs, but we'll probably have to wait a few weeks for that. 

While we were up in the hills looking at California pipevines, we also took a quick look at some of the oak (Quercus) and ceanothus (Ceanothus) for any polyphemus (Antheraea polyphemus) or ceanothus moth (Hyalophora  euryalus) cocoons, but unsurprisingly we found nothing as these species, especially H. euryalus, seem to have a very sparse distribution around here, and we don't have much expertise in finding wild cocoons in the winter. We also came across a California hop tree (Ptelea crenulata) beginning to regrow which might be useful for some swallowtails and Rothschildia sp. if we get any.

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Authors
Alan Liang

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