Pollinator of the Month: Ornate checkered beetle (Trichoda ornatus)

We previously featured the two-spotted lady beetle as a pollinator of the month since lady beetles benefit flowers through accidental pollination and through the pest control services they provide, however there are many species of beetles that pollinate flowers because they eat the pollen. There is a long history of beetles pollinating flowers as they existed before other common insect pollinators evolved. This includes soldier beetles, scarabs, long-horned beetles, sap beetles, and checkered beetles.

The ornate checkered beetle (Trichoda ornatus) is native to Canada. They are 5 to 15mm long, though they experience sexual dimorphism with the females being significantly longer. They are a metallic blue-black colour and a bright yellow to red blob-like pattern. They are also covered in long sparse hairs.

The genus name Trichodes refers to the hairs they are covered in and the word has Greek origins. The species name ornatus is Latin and refers to their decorated appearance.

They are found throughout Western North America, typically on flowers such as yarrow, asters, fleabane, daisies, buckwheats, cinquefoils, groundsels, or elderberries. This is because they lay their eggs on the flower heads. Once the eggs hatch, the larvae will attach to the legs of Hymenoptera, typically a leaf cutter bee or a potter wasp, who was pollinating the flower. The ornate checkered beetle is brought back to the nest of the Hymenoptera, where it enters a cell meant for the Hymenoptera larvae. Once the cell is sealed with food provisions and the Hymenoptera larvae, the beetle begins to feast. First eating the pollen and honey provisions then eating the Hymenoptera larvae. The ornate checkered beetle larvae eat 1 to 8 Hymenoptera larvae. They then pupate and overwinter in this state. When the adults emerge they feed on pollen from flowers.

yellow and blue-black ornate checkered beetle on yellow flowers

Posted on January 23, 2024 06:43 PM by kiarra13 kiarra13

Comments

Thanks for this useful journal post. I recently found Trichodes ornatus exploring Eriogonum douglasii flowers.

https://www.inaturalist.org/observations/221226989
https://www.inaturalist.org/observations/221231372

I assumed the beetle was eating the flower. I had not realized the lifecycle of this beetle, how it hijacks the nest of a Hymenoptera.

I did a bit of homework after I read your post and then the paper Observations on the Life History of Trichodes Ornatus by Linsley and Macswain which was available the at Cornell Library https://reader.library.cornell.edu/docviewer/digital?id=chla5077679_4204_004#mode/1up

E. G. Linsley, J. W. Macswain, Observations on the Life History of Trichodes Ornatus (Coleoptera, Cleridae), a Larval Predator in the Nests of Bees and Wasps, Annals of the Entomological Society of America, Volume 36, Issue 4, 1 December 1943, Pages 589–601, https://doi.org/10.1093/aesa/36.4.589

I made a sequence of events
T. ornatus year-long life cycle

1. Adult T. ornatus lays eggs on flower heads
2. Eggs hatch after 20 days, and beetle larvae emerge
3. Bee or wasp (order Hymenoptera) visit flower to pollinate
4. Beetle larva attache to legs of Hymenoptera
5. Hymenoptera returns to nest with stowaway larva
6. Beetle larva enters open cell in Hymenoptera nest
7. Hymenoptera provisions open cell and seals it
8. T. ornatus larva eats Hymenoptera larva
9. T. ornatus larva pupates during winter and emerges in spring
10. Adult T. ornatus emerge; find flowers and small beetles to eat
11. Female and male mate on flowers; female may consume male

Posted by brewbooks about 8 hours ago

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