A quick update on how the painted lady (Vanessa cardui) larvae that we collected in the Berkeley Hills 5/13/17 are doing.

It's been quite a while since we collected these painted lady caterpillars and they've made some good progress. After collecting them, we had put them on a live thistle (Cirsium sp.) in our backyard with a screen cage around them so we wouldn't have to constantly destroy their nests when changing their food if we were to rear them inside. We hadn't really paid attention to them since then and just let them do their business, and checking today, one had already pupated and the rest were mostly already in fifth and fourth instar.

We collected several painted lady (Vanessa cardui) larvae and eggs on thistle (Cirsium) up in the Berkeley Hills today.

Last year we didn't find too many Vanessa cardui despite the abundance of weedy thistles, as we weren't quite sure what season to look. Well, it looks like now is the season, as the thistles had many larvae and eggs today when we went up to the Berkeley Hills. The larvae were in early instars of various ages, and were all in conspicuous silk nests on the top sides of leaves. The eggs were small and pale green, though easy to spot, and were always on the center top of the leaf. In the end we had around 1-2 dozen larvae and some eggs. We didn't see any of the butterflies flying today, but we saw several last time we came. 

Today we took a short hike in Tilden Regional Park until we were just past Jewel Lake. There, we witnessed a completely different selection of butterflies than what we saw last summer in July. The first thing we saw was  west coast ladies (Vanessa annabella) and painted ladies (Vanessa cardui) which seem to be in large numbers during this time. These were mostly flying around tall grasses and nectaring. We also saw a male sara orangetip (Anthocharis sara), which is a species that we have never seen before. This is probably one of the only times that we have seen a pierid around here besides the cabbage white (Pieris rapae​) which we also saw on the way back. Also out of random chance, we also found a mylitta crescent (Phyciodes mylitta) and something that we cannot identify but looks vaguely like a some sort of Lycaenid. Both were flying among dead grasses and little weedy nectar plants away from the creek. 

We also observed one or two western tiger swallowtails (Papilio rutulus). One was around the butterfly garden which is right beside the creek while the other one (it could have been the same one) was flying along the creek past Jewel Lake. They flew by too quickly to distinguish either by physical characteristics or by behavior whether they were male or female. Despite not seeing any eggs, we also saw a single pipevine swallowtail (Battus philenor hirsuta) near pipevine, though we also could not tell if it was a male or female. 

​​Authors
Brian Liang

- Brian

Rearing notes for the single Painted Lady (Vanessa cardui), found either as an egg or caterpillar on wild mallow (Malva), that we identified among our West Coast Ladies (Vanessa annabella) after it molted to fifth instar.

Rearing notes 9/29/16-10/3/16:

- Brian

Today we realized we have a fifth instar Painted Lady (Vanessa cardui) caterpillar mixed in with out fifth instar West Coast Ladies (Vanessa annabella)!

Yesterday, while we were cleaning out the petri dishes that we our West Coast Lady (Vanessa annabella) caterpillars in, we took note of which ones were in apolysis as always and took care not to disturb them. We had quite a few -- maybe five or so -- fourth instar individuals in apolysis for fith instar. We noticed then, that one of them seemed much larger than the others, larger than perhaps a young fifth instar. At the time, it never once crossed our mind that it might be a Painted Lady (Vanessa cardui) caterpillar, which are normally significantly larger than V. annabella but today we found out!

The fourth instar in apolysis looks more or less identical to the V. annabella fourth instars, so it was no wonder that we didn't realize earlier. Even among different V. annabella caterpillars before the fifth instar, there is very little variation (there is incredible diversity in coloration in the fifth instar， though); every single caterpillar we had looked pretty much identical. We don't know exactly when the V. cardui caterpillar molted, but it must have been a while since we checked this evening because we almost jumped back when we opened our petri dish and saw a monstrous caterpillar towering over even the largest of mature V. annabella fifth instars. Besides the ungodly size, its appearance was now distinctly different than any V. annabella caterpillar. Its body much longer and less fat compared to V. annabella, more like a Red Admiral (Vanessa atalanta). In addition, its coloration actually is very similar to that of a typical black morph V. atalanta that we have never witnessed in any V. annabella; the base is completely black with not red or yellow striped down the back seen in all of our V. annabella, the spiracles are outlined in yellow, and the feet are reddish. At the same time, it also doesn't look quite the same as V. atalanta. See images below.

The strange part about finding this V. cardui caterpillar is that mallow (Malva) is not a particularly popular host plant. While V. cardui is probably one of the only butterflies in our area that are truly polyphagous, capable of feeding on low plants from a huge number of unrelated botanical families, it still seems unlikely that they would utilize mallow unless there is a population spike and food sources are in high demand, but V. cardui is certainly is not very common in our particular region at this particular time. A regional preferences for host plants is plausible but unlikely -- why would they compete with the abundant V. annabella which exclusively feeds on mallow? If anything, we would assume that V. cardui would more commonly utilize the milk thistles growing here but to this date we have never found one on this particular host plant in Albany. 

- Brian

Rearing Notes and Stats 7/27-8/3:

Alan, Brian

We found a Painted Lady chrysalis (Vanessa cardui) on the same thistle that we collected the two caterpillars before at Tilden Regional Park (Berkeley, CA).

This morning when we went to Tilden, the weather was very bad for finding butterflies. It was below 60 degrees, very cloudy, and there were occasional sprinkles. On the trail, the only thing we could really do was search for caterpillars or eggs. 

There are a lot of potential lepidopteran host plants at Tilden and the habitat is great since there is a creek and a lake to provide for riparian species. For trees, there are tons of willow (Salix), coast live oak (Quercus agrifolia), eucalyptus (Eucalyptus) and some conifers among a number of other trees. As for shrubs and vines, there is plenty of bramble (Rubus ursinus), stinging nettle (Urtica dioica), milk thistles (Silybum marianum), plantain (Plantago), and a whole bunch of other small plants.

What interested us most were the nettles and thistles which are favorite hosts of the Red Admiral (Vanessa atalanta) and Painted Lady (Vanessa cardui), respectively. There were the most nettles near the beginning of the trail but it was so dense and shaded that it would hard to find anything; and there presumably wasn't any because it all seemed rather uneaten with no leaf nests or frass as evidence for caterpillar inhabitants. There were a lot of thistle growing along the entirety of the trail, much of which was mature and flowering -- perfect nectar sources for butterflies had the weather been better. Last time we found two Painted Lady caterpillars on a rather isolated plant near the beginning of the trail that was covered in heaps of frass trapped in silk. 

After walking for half an hour and investigating every thistle plant we spotted, we only found two groups of plants that had any evidence of caterpillars: one was the plant from before and the other was a group of huge ones growing much further down the trail. Neither seemed to have any current inhabitants (the nests can stay for months after the caterpillar leaves if nothing destroys it). But when we took a closer look at the first plant, we noticed a Painted Lady chrysalis hidden deep within the thorny thickets at the base of a plant. 

Upon closer inspection, this chrysalis seems close to emerging. The fifth instar caterpillar that we found on this plant on 7/9 had already long pupated and emerged yesterday so this does make sense if they are in the same clutch; the outdoor temperatures are generally lower than indoor which hastened the growth rate and development of our caterpillar. If it is a male, than perhaps we can attempt to have them mate in captivity as we had our Gulf Fritillaries (Augraulis vanillae) do today. 

- Brian

The Painted Lady caterpillar (Vanessa cardui) that we collected from Tilden Regional Park (Berkeley, CA) on 7/9 has eclosed into the adult.

In exactly ten days since it pupated, the fifth instar caterpillar that we found on milk thistle (Silybum marianum) ​at Tilden Regional Park has eclosed into the adult (such speed that is!). It is a female.

The top row shows the very pharate chrysalis, just hours before it eclosed. The next two rows show it drying its wings in the sun while resting on a milk thistle in our yard. The last row shows a rare moment where it has opened its beautifully patterened wings; normally, the rest with their wings closed upright.

- Brian

Today as we were out picking thistle leaves, our Painted Lady caterpillar (Vanessa cardui) was killed by a European Paper Wasp (Polistes dominula)!

Ever since the European Paper Wasp (Polistes dominula) population exploded sometime last month when summer started, we have been having a huge problem with them killing our insects. This is not the first post that we have made about them (see here).  They actively search all suspect host plants from sun up to sun down and any living arthropod on the plants they search are doomed, large or small, unless they have some sort of defense such as a nest. The wasps seem to rely heavily on smell and are incredibly adept at discerning which plants tend to have defenseless caterpillars (milkweed [Asclepias] and fennel [Foeniculum vulgare] are favorites; on another note, they rarely go for trees).

They are very clever and will find their way into a rearing sleeve or bag if they are determined to attack what is inside. This year they have decimated our Monarch caterpillars (Danaus plexippus) and Anise Swallowtails (Papilio zelicaon) in rearing sleeves, attacked our Anise Swallowtail butterflies in an ovipositing enclosure, and even injured one of our Mediterranean Katydids (Phaneroptera nana) in a screened up enclosure. With this kind of killing power, they are undoubtedly the number one cause of mortality in caterpillars by predation. 

And today they found another victim to add to their list: our fifth instar Painted Lady caterpillar (Vanessa cardui) that we had found at Tilden Regional Park on 7/9. The older of the two we had found already pupated on 7/18 but the other one still had another day or so. But when we were picking some Milk Thistle (Silybum marianum) in our backyard for it, we made the bad mistake of leaving the caterpillar out unprotected. During the two minutes we turned our backs to pick, a European Paper Wasp came by and attacked. By the time we saw, the wasp had already bitten a whole in the caterpillar and within seconds, a huge pool of internal fluids were spewing out of the wound. Of course, we got the wasp away to see if it was still saveable but from the looks of it, the damage had already been done and the caterpillar would soon bleed to death. Within a few hours after we took it back in, it died. 

To conclude, NEVER leave caterpillars (or other insects) unprotected outside if you have wasps roaming around your area, even for a few moments. 

- Brian