Posts Tagged ‘caterpillar development’

Tachinid Flies

June 10, 2015

Last month I found a caterpillar hanging in the “J” position from the wall on the side of my house — I thought “Oh good, my first butterfly is coming!”.

A couple of days later this is what I found:

Jun2015_Tachinid5

 

I could not imagine what had happened to it — especially since a few days earlier I had discovered another caterpillar in similar condition hanging from one of my succulents. What was going on?

The key, it turns out, is the little white string coming out of the bottom of the caterpillar. This is the tell-tale sign that the caterpillar has been infected by the dreaded Tachinid Fly.

Tachinid flies are parasitoid insects, meaning they lay their eggs in other insects. For this reason, they are generally considered “beneficial” insects, in that they can destroy pests without the need for pesticides. Unless, that is, you don’t consider Monarch caterpillars to be pests. These flies deposit their eggs in the growing caterpillars. They don’t kill the caterpillar immediately — usually the fatal blow comes after it has attached itself in order to pupate, or sometimes even after it has formed a chrysalis. Then the eggs hatch and the pupae exit the creature by means of the aforementioned string. Unfortunately, I haven’t been around to see the actual exit, so I have been unable to destroy the pupae. That means they have likely developed into even more flies.

From what I have read, 17% of Monarch caterpillars are destroyed by Tachinid flies. I guess I’ve been lucky up to this point … I haven’t had any until this year.

Here are some of the other victims of this insidious creature I’ve found around my yard:

Jun2015_Tachinid4

Jun2015_Tachinid1

Jun2015_Tachinid2

 

Altogether I’ve lost at least seven caterpillars so far. I don’t know what to do about it, except to ride it out. There is precious little literature about how to get rid of this pest, seeing as it is considered a beneficial predator by most gardeners!

I have had two butterflies so far this year, one on the top of my garage door:

Jun2015_ButterflyGarage

The other one emerged just this morning from a chrysalis on my neighbor’s gate, and flew off before I had a chance to immortalize her on film.

I can only hope that these flies disappear at some point!

 

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Two-month Butterfly Summary

November 20, 2013

Much to my surprise, we have had three more generations of butterflies since the last time I posted. I really thought that the huge 46-caterpillar eruption had exhausted the milkweeds, and that they would not recover in time to be able to support more butterflies … but I was wrong! They “re-leafed” in a matter of a few weeks, quite handsomely.

I’ll go through a fairly brief summary of the new generations.

First generation, late August/early September:

This generation had only 5 or 6 caterpillars, and only 3 of them pupated (that I could find).

The first pupated on the wall:

Aug2013_Chrysalis1

The second pupated on the wall post:

Sept2013_Chrysalis3

The third could not seem to find a horizontal surface and settled for hanging off the back of the sign at an angle:

Sept2013_Chrysalis2

The second butterfly emerged without any problems and flew off routinely:

This is a male.

This is a male.

The first butterfly hatched normally and seemed to also be on its way to a routine maiden flight. I took note of it and went out for coffee.

When I came back, at first I could not see the butterfly, and assumed it had flown off. But then I looked more closely, and discovered it on the ground underneath one of my coffeeberries, entrapped in a spider web! I assume it had fallen off, and run into the spider web while searching for a vertical surface to climb onto. The poor thing was struggling hopelessly. We have had a LOT of spiders this year, for some reason.

My boyfriend Hank and I extracted it from underneath the coffeeberry, and attempted to remove the remnants of the spider web, which were very strong. There was one strand attached to its leg, and I was afraid to try to yank it off, lest the leg come off as well! I ended up cutting it off with nail scissors as close to the leg as possible.

We finally got most of the spider web off, and got the butterfly to cling to a washrag hanging vertically from my bench, where it remained for several hours while its wings dried. However, the wings seemed odd to me — although they appeared normal visually, the hindwing would not stay under the forewing the way it’s supposed to when the butterfly flapped its wings. I was worried that they were damaged.

My fears appeared realized when late in the day it attempted to fly, and did not seem to be able to go more than a few feet, flopping to the ground rather than landing gracefully. It flopped around some on the path:

Sept2013_Butterfly1

I considered euthanizing it — but decided to bring it into the house for the evening, in the hope that its wings just needed to mature a bit.

The next morning I took it out into the sun — and to my great relief, it flew off quite normally!

Moral: don’t give up too soon on an apparently wounded butterfly!

The third butterfly, alas, did not survive — it died within the chrysalis, turning black:

Sept2013_Chrysalis2a

My theory is that the hot sun baked the metal of the sign and proved too much for the developing butterfly. We had a major hot spell in September, with temperatures into the 100s for weeks, including uncharacteristic high humidity levels.

Second generation, early October:

This generation, again, had caterpillars in the single digits. Again, only three survived to pupate.

The first one pupated on my Evergreen Currant plant, near the front door:

Oct2013_Chrysalis1

The second pupated on my Ceanothus on the mound. The chrysalis was so close to the ground that I didn’t think the butterfly would be able to drop down properly, so I raised up the branch and attached it to a stake for the time being:

Oct2013_Chrysalis2a

The third pupated on my Winifred Gilman sage:

Oct2013_Chrysalis3a

Oct2013_Chrysalis3b

When it came time to hatch, this chrysalis went first. Unfortunately, we were having a major windstorm, with sustained winds of 50-60 mph, and gusts of up to 80. They were among the strongest winds I’ve experienced in my 40 years in Southern California! When I came out in the morning to check on the chrysalis, it was open, but the butterfly was nowhere to be seen. I have to assume it was blown away by the wind!

The other two did not hatch until the next day, when the winds had died down (thankfully!). They were fine specimens and flew off normally:

A fine male.

A fine male.

A female.

A female.

Third generation: late October — the “pumpkin” batch:

OK, I really thought that was the last generation, as we’re getting close to the fall rains! Au contraire! The plants revived quickly, and we had a MAJOR caterpillar baby boom:

Oct2013_Caterpillars

I counted 24 in this generation, but there were probably more than that.

As you can see in the above picture, these caterpillars decimated the milkweeds — even more, it seemed, than the previous 46. Perhaps the foliage had not come back as strongly. At any rate, at one point there were virtually NO leaves left, and yet very few of the caterpillars had reached maturity. They were leaving the plants, but not to seek pupating spots — instead, they were desperately searching for more milkweeds! I directed some of them to the plants with the most remaining leaves, but eventually there was no place left to move them.

Panicked, I made a quick trip to Armstrong Gardens searching for another milkweed plant, but they were out — as I expected, since they usually don’t carry them except in the spring.

I searched the web to see if there was anything I could do — and found a Monarch forum in (of all places) New Zealand, where Monarchs are apparently very big. I found a thread in which a poster was facing the same problem — he had run out of milkweed leaves. And some respondents were claiming that in a pinch you could feed monarchs chunks of pumpkin, and they would eat it!

They asserted that all the caterpillars would eat the pumpkin, but only the largest would survive to pupate. I decided I had nothing to lose, and since it was October, pumpkin fortunately was not hard to find! Sure enough, they attacked it ravenously:

Oct2013_Pumpkin

At one point there must have been 10 -15 caterpillars on the various chunks of pineapple I had laid out.

But although a number seemed big enough to pupate, only three ended up doing so. I’m not sure what happened to the others — some of them died and I found their bodies, but others just seemed to disappear.

Here are where the three ended up:

I had put up two trellises for the caterpillars.

I had put up two trellises for the caterpillars.

I didn’t take pictures of the two other chrysalises, but they were both on the wall, and both butterflies emerged successfully and flew off. One of these, by the way, was a “pumpkin” caterpillar, proving that this is indeed a viable solution:

The pumpkin caterpillar

The pumpkin caterpillar

The one that pupated without pumpkin

The one that pupated without pumpkin

Alas, the chrysalis on the trellis did not make it. It was developing normally, becoming darker and eventually transparent, but for whatever reason it reached the point of emergence in the middle of the night, when we were having a rather cold spell. I think the added moisture in the air at night was what doomed it, probably even more than the temperature. The outside of the chrysalis needs to be brittle and dry in order to break away properly — if it is moist, it seems to become too stretchy. At any rate, the butterfly became “stuck” and did not fall out:

Nov2013_Chrysalis1a

But I was happy that at least I managed to save two of the butterflies.

I don’t think we will have any more butterflies this year!

46 Caterpillars => 18 Chrysalises

July 26, 2013

That’s right — my previous estimate of 15 caterpillars was way, way off. Once the milkweed plants were stripped of their leaves, it became much easier to see the caterpillars, and I counted 46 (more or less!). To refresh your memory, here are some of them from about a week ago:

July2013_caterpillars10

 

July2013_Caterpillars11

 

 

I have no idea why there were so many caterpillars this year! Normally, I have 5 or 6 at a time, perhaps 2 or 3 times a year. Was it the heat? The unusual mugginess we’ve been having this year? Who knows!

At any rate, there were really too many caterpillars for the plants to support. They ate the milkweed plants down to the nub of each leaf, and soon began eating the stems. Many of them were too immature to pupate at this point. Some started crawling away from the plants, but I knew they were not ready to pupate — they were looking for another milkweed plant. I was able to move a few of them to a small milkweed plant a few feet away that the butterflies had ignored — probably because it was too small. In addition, I moved some of them to the three new, small plants on the side of the house. They ate those, too, down to the stems.

Here is what the three major plants ended up looking like:

July2013_Milkweeds

 

In the end, many of the caterpillars that were too small ended up perishing, though I don’t know where or how in most cases. They simply disappeared. A few of them were attacked and killed by ants when they came down to the ground from the small milkweed — it was, apparently, located in the middle of an ant path. Some others seemed to simply succumb to the heat; I found dead caterpillars exuding fluid in a couple of places. The others met their end hidden from my sight.

The lucky ones — the ones that had reached full maturity before the leaves gave out — went off to find places to pupate.

One of them chose an unfortunate spot: this caterpillar had been one of the ones i had moved to the side of the house, and he ended up climbing the stucco wall of the house to try to find a pupating spot. Unfortunately, he could not find a horizontal surface — alas, there really aren’t any on that wall — and he formed the “J” on the vertical wall, hanging off at an angle. One of my previous caterpillars had done a similar thing a few weeks ago, and encountered no problems — but that caterpillar was attached to a wooden part of the wall. This caterpillar was attached to the stucco. When he went through the process of forming the chrysalis, which involves a lot of twisting and turning, the roughness of the wall apparently tore his body apart. I found the remnants of his body and a dwarfed, misshapen chrysalis. The picture is kind of disturbing, and I won’t post it. But I think next year I may put up trellises on that wall, so the caterpillars who end up on that wall will have an easier time of it.

The others — well, in short, I found 18 chrysalises! Here is where they are located:

Hanging from the wall overhang.

Hanging from the wall overhang.

There was one behind the box near the bottom of the wall.

There was one behind the box near the bottom of the wall.

One attached himself to my neighbor's potted plant.

One attached himself to my neighbor’s potted plant.

One pupated on one of my Asters.

One pupated on one of my Asters.

Five ended up on the wall post!

Five ended up on the wall post!

One ended up -- AGAIN! -- on my wheelbarrow, and the other on the overhead beam.

One ended up — AGAIN! — on my wheelbarrow, and the other on the overhead beam.

One crawled all the way to my Winifred Gilman sage.

One crawled all the way to my Winifred Gilman sage.

Last but not least, one found one of my Royal Penstemon plants.

Last but not least, one found one of my Royal Penstemon plants.

And here are a few of them in closeup (just a few, in keeping with the observation that they all look more or less alike!):

# 4, behind the box.

# 4, behind the box.

#5, on the plant.

#5, on the plant.

#6, on the Aster.

#6, on the Aster.

 

The crowded four-plex on the corner of the wall post!

The crowded four-plex on the corner of the wall post!

The loner on the other corner.

The loner on the other corner.

 

This guy must be able to read!

This guy must be able to read!

#15, on the other arm of the wheelbarrow.

#15, on the other arm of the wheelbarrow.

A tiny one on the Winifred Gilman.

A tiny one on the Winifred Gilman.

 

#18, on the Royal Penstemon.

#18, on the Royal Penstemon.

It’s probably not obvious, given that it’s hard to determine scale looking at these close-up pictures, but quite a number of these chrysalises are tiny — considerably smaller than normal chrysalises, reflecting the fact that many of these caterpillars, though ostensibly mature (officially, at the “5th instar”), were smaller than usual . The one on the Winifred Gilman is especially small, only about 3/4 inch long. Possibly it’s because of the extreme competition for food this time. It will be interesting to see if the butterflies that emerge are correspondingly small.

I expect these butterflies to make an appearance in the next week. That could be a crowded scene. Stay tuned!

Second “Wheelbarrow” Butterfly Hatches

July 23, 2013

Last Friday the latest butterfly — the second one to pupate on my wheelbarrow — decided it was time to bring her gorgeous self out.

For the first time, I was able to photograph her right after emergence. When Monarchs first emerge from the chrysalis, their wings are very small, and their abdomen is engorged with fluid:

July2013_NewButterfly1

 

July2013_NewButterfly2

 

(It’s a good thing I added the terrycloth — I don’t think the butterfly would have been able to cling to the large steel bolt underneath the terrycloth covering.)

Over the next 10 minutes or so — it did not take long — she pumped fluid into her wings until they were almost normal size:

July2013_NewButterfly3

 

July2013_NewButterfly4

 

July2013_NewButterfly5

 

She stayed in more or less this state for a couple of hours, just sitting and allowing her wings to dry off and become stiff enough to be useful — and then she took off. Another beautiful, healthy Monarch in the world!

Tomorrow (I hope) I’ll begin telling the story of the 46 caterpillars (yes, 46!) that populated my meager collection of milkweed plants!

Traffic Jam!

July 17, 2013

I can’t resist posting this:

July2013_trafficjam

It won’t be long now before quite a few of them take off!

Caterpillars Galore

July 16, 2013

Well, I thought the caterpillar season was “over” because the presence of the wasps would nip the population in the bud — decidedly not so!

First off, there was a mature caterpillar a week or so ago who wandered off the plant to seek a suitable pupating spot just as I had to go to a doctor’s appointment — thus I missed seeing where he ended up. After I got back, I looked everywhere — or so I thought — and could not find him.

But just a couple of days ago, my boyfriend Hank pointed out a new chrysalis — on the wheelbarrow again, very near the one from a month or so ago. Here it is:

July2013_chrysalis1

 

July2013_chrysalis2

 

This picture shows the terrycloth I added around the pupating spot, because I feared that the metal would be too slick for the butterfly to get a purchase on, once it emerges. This caterpillar did not choose the best spot; newly emerged butterflies want to crawl UP after they have pumped up their wings while clinging to the spent chrysalis. This position, inside the “groove” of the wheelbarrow leg, means the butterfly cannot go directly up; it will have to step to the side somehow. We’ll see how it goes.

A few days ago, I wandered over to the milkweed plants for the first time in weeks, and discovered a treasure trove of caterpillars growing on them! Yesterday I counted at least 15. Just in this picture alone, I can count 8:

July2013_caterpillars1

 

Other pics:

July2013_caterpillars3

 

This one is probably the closest to maturity.

This one is probably the closest to maturity.

Unfortunately, as I was checking out the caterpillar collection, I noticed one of the WASPS was on the plant — and eating one of my caterpillars! The poor thing was long dead, and the wasp was finishing his meal. I had in my hands a pair of scissors I had just been using to cut up the terrycloth, and I swiped them at the wasp, trying to cut him in two! Alas, he flew away.

This is going to be a problem, and no doubt all these caterpillars will not survive. Already, since this wasp encounter, I have found the bodies of two caterpillars who have no doubt fallen prey to one of the wasps:

July2013_Wasp1

 

July2013_Wasp2

 

I am loath to surround the plants with netting as I did last year. The caterpillars are all in different stages of development, and it would be difficult for the mature ones to escape the netting to seek a pupating location without removing the netting and endangering the others.

So I am just going to monitor the situation. I’ve been checking the plants every few hours, and when I see a wasp I try once more to cut it with the scissors! I also have some wasp spray, but I don’t want to spray them when they are on or near the milkweed plants, lest the spray harm the caterpillars or contaminate the plants. No doubt some more will be lost.

If it looks like the wasps are taking too many of them, I may reconsider on the netting.

In the meantime, we may have another generation: while I was photographing, a butterfly happened by and deposited some eggs:

July2013_butterfly1

 

Just a quick update this time. The garden is going into its summer dormancy and doesn’t look too great — the typical turn of events with California natives. For those who’ve been trained to think that a garden should always look green and have something blooming, this can be a hard phase.  But this, after all, is the natural situation for our climate. It’s so much better to keep things as close to their natural state as possible, and just give a little help (water-wise) so they don’t fall into a completely dry state. Learning to appreciate the natural stages of the flora and fauna of your environment makes you feel so much closer to it!