A Straight-snouted Weevil

Baptisia alba
Baptisia alba Seedpod

Almost reflexively, I pull the baby rattle-shaped seed pod from the stately White Wild Indigo (Baptisia alba) as I meander through Shaw Nature Reserve’s prairie trails.  I can’t help it.  I make sure the pods are always black, mature and any seeds left unravaged I simply help to disperse along my walk.  But in doing this so often in the late summer and autumn for so many years I have come to notice that this common forb cannot disperse many seed.  Because, inside the seed pods, like the one pictured above, I usually find multiple seed predators – the short-snouted weevils, Trichapion rostrum (Family Brentidae).

Trichapion rostrum
Trichapion rostrum

Baptisia seed are favored among other insects as well, but what they may lose in this stage of life, they pick up as they grow, for the false indigo are long-lived, drought-tolerant perennials that contain large amounts of secondary compounds that make them absolutely unpalatable to grazing mammals.  The photo below shows these tiny beetles (3.0 – 3.5 mm) among the husks of a number of seeds.  I have not been able to find a source that suggests if both larvae and adults feed on these seeds, or just one of the growth stages.

Trichapion rostrum
Destroyer of Seeds

Here is an image of a couple, shortly after I split their double-wide…

It's the Visitors, Martha!
It’s the Visitors, Martha!

These little one have been a source of fascination for me.  I hope to learn more about them someday.

-OZB

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