Thimbleberry hideaway

They're a sort of slow cooker, with a 2-year timer. Thimbleberry galls.

Large gall on a thimbleberry stalk.

I've looked at them before, in the winter, when the leaves are gone and the stalks are dead and brown. The galls then are hard and brown; very hard, difficult to cut open. Chickadees pound away at them until they break through.

Two-year-old galls, mid-winter, 2019. Chickadees have been at the one on the right.

A gall, split open, with two larvae visible.

These are the larvae of the thimbleberry stem wasp, Diastrophus kincaidii. They are tiny; about 3 mm. long.

Diastrophus kincaidii lays many eggs (as well as the chemical compound which forms the gall) into the stem of the thimbleberry. Once the gall is formed, it feeds and protects the larva for 2 years until they emerge as adults. (Raven's Roots Naturalist School, Facebook post.)

The galls form on the green canes, which are soft, but the chickadees wait till the second winter, and break into the hardened galls, probably because the larvae now are fat and juicy. Good eating! (If you're a chickadee.)

The larvae that don't get eaten bore their way out of the gall in the second spring.

And here's one of the wasps that emerged from these galls in March:

More wing than wasp 

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Comida a cocina lenta. Son las agallas que se forman en Rubus parviflorus, un arbusto nativo muy común en la zona del bosque templado húmedo.

Primera foto: una agalla grande en el tallo de un Rubus parviflorus.

Las he observado antes, en el invierno de 2019, cuando las agallas estaban secas y duras. Muy duras; me costó trabajo cortarlas. Los pájaros chickadee las golpean repetidamente hasta romperlas.

Segunda foto; una de las agallas en el invierno.

Tercera foto: una agalla cortada por la mitad, mostrando dos larvas vivas adentro.

Estas son las larvas de la avispa de las agallas, Diastrophus kincaidii. Son muy pequeñas, unas avispas que miden aproximadamente 3 mm. de largo.

"Diastrophus kincaidii pone muchos huevos (y también el compuesto químico que estimula el crecimiento de la agalla) en el interior del tallo de Rubus parviflorus. Una vez que se forma la agalla, este alimenta y protege las larvas por 2 años hasta que emergen como adultos." (Raven's Roots Naturalist School, Facebook post.)

Las agallas se forman en los tallos verdes, que son tiernos, pero los pájaros chickadee esperan hasta el segundo invierno, cuando las larvas ya están gordas. ¿Buen provecho! (Si eres chickadee.)

Las larvas que sobreviven taladran una salida al exterior en la segunda primavera.

Cuarta foto: una de las avispas que emergieron de estas agallas maduras en marzo de 2019.

New-born thimbleberry wasps

A month ago, I collected a few thimbleberry galls, brought them home, and split one apart to look at the larvae hidden inside. (Story, here.) I stashed them afterwards in a plastic container and set them aside in a cool spot.

This week, I opened the container. And several tiny wasps have burrowed their way out.

The larvae as they were a month ago.

Another one of the galls, this week, with exit holes.

And one of the newly-emerged wasps, Diastrophus kincaidii. About 2.5 mm long.

Another one, bent over, showing off her wings.

Wasp # 3. Wasps have that tiny waist; it seems strange that it can support the weight of the heavy abdomen.

I just checked again. There were three galls, all on the small side. And now there are a dozen new wasps, freshly emerged. I left the lid off; I don't know where they'll go, since I have no thimbleberry canes nearby. Maybe they'll find an alternate host in the raspberries.

Gourmet chickadee feed

Years ago, when I lived on a hillside overlooking Silvermere Lake, my living room windows faced a stand of thimbleberry bushes. During the winters, I watched a flock of chickadees that spent their days pounding away at the hard galls on the bare thimbleberry canes. It was hard work, but they persisted, in spite of the easier feed of of black oil sunflower seeds a few metres away. Easier, but obviously not as tasty.

On the road to Deadstick Pond, I stopped to examine a collection of galls.

Gall on bare thimbleberry stem. This one has exit holes.

Two galls, mostly intact.

And the chickadees have been working on the one on the right.

I collected a few galls to examine more closely at home.

Gall with many exit holes. I cut it in half and saw ...

Holes where the larvae had been. The centre of the gall is the original stem of the thimbleberry.

And then I cut open one of the intact galls; it had residents.

Two pretty larvae visible, hints of another deeper inside.

These are the larvae of the thimbleberry stem wasp, Diastrophus kincaidii. They are tiny; about 3 mm. long. (See UBC photos.)

Gravid female D. kincaidii prefer to ovi-posit in the  relatively soft, rapidly growing shoots of primocanes, which often host  clutches  of  eggs from  multiple female  wasps (Wangburg  1975). Green, irregularly shaped galls form as larvae begin to feed during the rst season and adults emerge from woody galls early in the summer of year two. (From Research Gate)

The galls form on the green canes (photo), which are soft, but the chickadees wait till the second winter, and break into the hardened galls, probably because the larvae now are fat and juicy. Good eating! (If you're a chickadee.)

I stashed the galls in a plastic container; I'll be watching to see what adults bore their way out.