October 18, 2022

e-polycarpa-tubular-gall

In 2012 I first ran across some banana-shaped objects growing on Euphorbia polycarpa plants:

I vouchered the plant material and dissected some of the objects finding only tiny orange larvae which I could not identify. I have occasionally seen the galls since, but this year they have been produced in great numbers, with thousands of them felicitously placed within a few feet of my back porch. Spot-checks in other locations and another observation suggest this has been a particularly good year for the insects involved.

Euphorbia polycarpa is a member of the Euphorbiaceae. The floral structure of euphorbs is unique to the family. A cuplike involucre holds a single stalked female flower at its center, surrounded by one to dozens of male flowers. Male flowers are reduced to just a stalk with paired anthers at the ends. This arrangement is called a cyathium:

The galls are induced in the cyathium of the plant by the act of the galling insect laying its egg. The cyathium itself grows abnormally; glands and appendages normally produced on the rim of the cyathium can be seen at the apex of some galls. The walls of the gall encapsulate the egg, larva, and pupa. The distal end of the gall is open.

Thus began a hunt for the inducer. In near-daily safaris among a dozen or twenty galls at a time, I found almost nothing beyond those familiar orange larvae. The larvae were usually single, but there were multiples in a few, as many as four in a single gall. The larvae were all identical, at least to my untrained eye. Along with near-daily harvests, I placed some material with galls in petri dishes hoping for adults to emerge. Eventually some pupae turned up (images are linked to the observations):

At least two adults were found firmly ensconced in galls, one alive and one not:

All four had the head to the distal end of the gall. Note the ovipositors on the dead adult and pupae. Given the length of the ovipositors, this taxon could be a parasitoid - a parasite on a parasite. With the open end of the gall, they would not even need to perforate the gall wall.

The pupa at right above produced this adult:

All adults are similar, but not identical. Body length of all is similar, just above 2 mm. Some variations:


Female, dorsal view


Male [?] with feathery antennae

The above were found in the galls or resemble those that were. Whether they represent more than one taxon I don't know. I've been sticking with Chalcidoidea, and even that may be wrong with some of them; I'm out of my depth.

Some other wasp or wasp-like insects turned up in the petri dishes. This small wasp is very active and difficult to photograph:

It is the next most numerous wasp. Body is about 1 mm long. Began appearing later than the others, and seems to be thriving in the dishes.
ETA: This appears to be a whitefly parasitoid in the genus Eretmocerus; makes sense since whiteflies are also very common on the E. polycarpa plants. Information at the link (click on photo above).

Beyond those a couple of other wasp-like critters made brief appearances, one each:

Colorful things; possibly the same taxon. Both had bodies of about 1 mm long. Deceased at left, alive at right.

I found galls similar to the Euphorbia polycarpa galls on Euphorbia melanadenia, nearly identical except for the hairs on the outer surface of the galls. The hairs are consistent with that species' usual indument:

There are other images of similar galls on related taxa here and I know there's at least one more out there - will add if found.

I've accumulated quite a pile of adult corpses - couple of dozen so far - if anyone is interested and able to attempt to further ID these critters. There are also links to other observations I made in the hunt here, compiled by the ever-helpful Nathan Taylor, creator of this relevant project.

Bottom line: I have no idea which, if any, of these wasps are inducing the galls.

Posted on October 18, 2022 02:36 PM <span class="translation_missing" title="translation missing: en-us.by">by</span> stevejones stevejones | 5 comments | Leave a comment

September 12, 2022

Euphorbia polycarpa tubular galls

This gall is one I've seen before on Euphorbia polycarpa in the area, but this year there are literally thousands of the things densely covering many individual plants, many of them within handy reach just off my porch. I've been trying to raise the galls with some success, though I'm not sure I've capture the responsible organism. Larvae are all similar and are included in the first observation below; there is also a pupa, bearing some similarity with the chacidoid wasp. First adults to appear were the parasitoid chalcidoid wasp linked below. Next was the smaller four-winged insect also below. I'm at a loss to ID that one even to order. The individual photographed has some coordination issues. Photos aren't great, but equipment is limited and depth of field suffers.
I also found similar galls on Euphorbia melanadenia in a branch of Rackensack Canyon (third observation).

Posted on September 12, 2022 11:57 PM <span class="translation_missing" title="translation missing: en-us.by">by</span> stevejones stevejones | 5 observations | 1 comment | Leave a comment

February 15, 2022

Pin and thrum heteromorphy in Lycium exsertum

Some time ago @emaking introduced me to pin and thrum floral heteromorphy, in which either male or female flower parts in normally perfect flowers are alternately suppressed. Lycium exsertum and its cousin L. fremontii exhibit heterostyly; some of them are functionally dioecious. All flowers of an individual shrub are either:
1) Perfect - male and female parts well-developed
2) Pin flowers with short filaments, reduced anthers and a normal pistil producing functionally female flowers
3) Thrum flowers with short pistil length and anthers large and well-exserted resulting in functionally male flowers

I ran a short survey of the L. exsertum plants on my property, 33 plants, all in flower. Of those, 7 have perfect flowers, 12 have thrum flowers and 13 have pin flowers. Pin flowers were generally smaller than perfect and thrum flowers, both shorter and narrower. In addition there was one plant expressing poor development of both male and female parts, representing a fourth condition to add to the list above.

Posted on February 15, 2022 10:06 PM <span class="translation_missing" title="translation missing: en-us.by">by</span> stevejones stevejones | 0 comments | Leave a comment

January 16, 2022

Fringed-cup gall adult

An adult emerged from one of the galls in this original observation. Good to see after rescuing the galls from a fungus that was spreading mycelia around the galls in their original container (I'm not good at this sort of thing). I'm resigned to euthanizing the thing if there is some place I can send the insect for further identification. Also curious how best to preserve it. Any advice would be appreciated.
@megachile @nancyasquith @calconey @jeffdc @ceiseman

Posted on January 16, 2022 01:08 AM <span class="translation_missing" title="translation missing: en-us.by">by</span> stevejones stevejones | 6 comments | Leave a comment

December 20, 2021

Who knew?

In all the years I've been staring into creosote bushes, I never noticed that the leaves have hairs until I noticed them in these photos. The angle of the lighting made them stand out, especially at the lower left. The hairs are appressed and covered with the waxy leaf coating for which the shrub is famous, but scratching lightly at the surface, or soaking leaves in alcohol, will reveal the hairs.

Posted on December 20, 2021 05:06 PM <span class="translation_missing" title="translation missing: en-us.by">by</span> stevejones stevejones | 1 comment | Leave a comment

December 10, 2021

Germinating rain

Much of Arizona had good rains yesterday, the first rainfall since October 5th at my location. We had 0.60" overnight, which ought to be enough to kick-start germination for spring wildflowers and grasses. Another season begins.

Posted on December 10, 2021 04:58 PM <span class="translation_missing" title="translation missing: en-us.by">by</span> stevejones stevejones | 5 comments | Leave a comment

November 07, 2021

Baileya multiradiata and Trigonorhinus fungus weevils

When collecting seeds of desert marigold (Baileya multiradiata for you latin fans) I more often than not run across fused clumps of seeds in the seedheads that have been partially eaten and abandoned leaving a chamber and frass behind. This week as I was gathering some I found larvae and later adult fungus weevils (Trigonorhinus) in those chambers. The best match looks to be Trigonorhinus griseus, but being out of my field I'm reluctant to call a species.

As noted the chambers are quite common. This morning I collected and dissected ten likely seedheads (well-dried and shedding old flowers), and found the following:

Larva 2
Pupa 0
Adult 5
Empty chamber 2
No chamber 1

Nine of the ten had chambers. Larvae and adults were alive and were returned to their hosts.

If you have access to plants with mature seedheads (see attached photos), I'd be interested in a count of ten looking for evidence of a chamber (some of the seeds firmly clumped). If you want to go further and open them looking for occupants all the better.

Posted on November 07, 2021 04:07 AM <span class="translation_missing" title="translation missing: en-us.by">by</span> stevejones stevejones | 3 observations | 2 comments | Leave a comment

October 21, 2021

New creosote bush project

In the process of searching for creosote bush galls I stumble upon many other creatures that utilize creosote bushes. It occurred to me to set up a companion project to the creosote bush galls project focusing on those miscellaneous creatures. Organisms Associated with Creosote Bushes is a place to put those observations. Spiders, grasshoppers, tree hoppers, caterpillars, beetles, ants, galls (except for the known species of Asphondylia gall) and other creatures can be included there. For obvious reasons this is a traditional project to which the observations are added manually (rather than automatically as with the creosote bush gall project). There is one required field, Type of Association with Plant; select the most appropriate response from the menu.

Posted on October 21, 2021 02:19 PM <span class="translation_missing" title="translation missing: en-us.by">by</span> stevejones stevejones | 5 comments | Leave a comment

October 01, 2021

Gall Week

With Gall Week beginning tomorrow, I scouted some of the local creosote bushes for galls. There were very few, but other things made up for it. Four caterpillars and a couple of spiders caught my eye. Kinda surprised me to see that many caterpillars living on creosote bush.

Posted on October 01, 2021 03:22 AM <span class="translation_missing" title="translation missing: en-us.by">by</span> stevejones stevejones | 6 observations | 0 comments | Leave a comment

September 27, 2021

Local grasses

Site reconnoiter for potential as tour site of native and non-native grasses; focus is on perennials but there are a couple of native annuals tossed in.

Posted on September 27, 2021 06:03 PM <span class="translation_missing" title="translation missing: en-us.by">by</span> stevejones stevejones | 9 observations | 1 comment | Leave a comment