Bug of the Week 5/18/2023

This week’s bug of the week is the lady beetle, Hippodamia convergens. If you’ve ever looked into buying lady beetles as a biocontrol, this is probably the species sold. About this time every year I see a post, or am asked about using lady beetles for controlling aphids and such in the garden. And, I suppose every year I may make a post about why you should not. To begin with, this species is not native to Alaska. So, purchasing them and releasing them is really introducing a non-native species. Like the Boa in Florida, or pigs in Texas, they can become a real problem. The second is they are not reared. They are collected in the wild where the species aggregates to ride out the winter. People just come along and take thousands from their winter sleep to sell. This has decimated population in their native range in the Sierra Nevada. Could you imagine going and taking thousands of Monarch butterflies from the trees in Mexico? Many of the online “sellers”, even on Amazon, are not reputable agents and lack proper business licenses or permitting to sell to Alaska.

My other reason is they don’t work. Being that they were taken from their period of torpor, they first want to feed for a week or two, then migrate. Some will be sold as already fed, so they really just want to leave. This is one reason why they don’t work. If you release them in a garden they will leave. If you contain them in a greenhouse, they will feed for a few days, then try to migrate, then lay eggs. Then you have to wait for the eggs to hatch, and the larva to grow. So, the only impact they will make is when the adults feed that first week and then when the larger larva feed a few weeks later. Add to this they are not all that impactful when they do stay around. Studies have found much higher concentrations are needed than what suppliers recommend to be effective. In the greenhouse 200-350 beetles are needed per plant for noticeable aphid control. In the outdoors, try 2000 per plant. So, if you have 10 Dahlia you’re trying to protect from thrips, that’s a $500 gamble. Whereas cheap and reliable cultural or synthetic options are much, much cheaper. There are other reasons, like competing or introducing pathogens to our native lady beetle fauna which are also good reasons. Really, it’s just not a good idea, regardless of what the Facebook says.

Joey Slowik, IPM Technician
jaslowik@alaska.edu

You can submit unknown pests (plants, insects, diseases, etc.) through the UAF Citizen Scientists Monitoring Portal: www.alaskapestreporter.org

Photo: Mass of convergent lady beetles in Alamo Peak, Otero Co., NM. Photograph by Jerry Oldenettel.

Native Lady Beetle Highlight – The Eye-spotted Lady Beetle (Anatis mali)

The Eye-spotted Lady Beetle is one of our largest species of lady beetles in Alaska. This pretty giant can grow up to nearly a centimeter long and features a red to brown body color with many black spots that are each surrounded by a pale ring. This species is encountered throughout both interior and southcentral Alaska, though it seems to be more commonly observed in the interior. This lady beetle is an important predator of aphids and other small insects in trees, both in conifers and hardwoods. In spring they are often observed on trunks of birch or aspen where their red bodies stand out against the white or grey tree bark. If you look closely you might even see one laying a cluster of oval-shaped, orange eggs on the tree!

Native Lady Beetle Highlight - The Two-Spotted Lady Beetle (Adalia bipunctata)

The name “two-spotted lady beetle” is a little bit of a misnomer here in Alaska. The typical form of this lady beetle has nice orange to red wing covers over the back (called ‘elytra’), each with a single black spot. However, this species has a beautiful variety of different color patterns, and different individuals of this species might have anywhere from 0 to 14 spots! Here in southcentral Alaska I most often see the versions with a row of spots in the middle of the elytra and another near the rear of the elytra, which are sometimes coalesced into a wavy band as shown in the photo.

The two-spotted lady beetle prefers hanging out in trees and shrubs where it feeds on aphids, mites, insect eggs, and other small, soft-bodied insect prey. In spring, adults may also feed on pollen, nectar, or honeydew for energy.

This species has been in decline in many parts of its native range, both in North America and in Europe. Factors such as habitat loss, competition from introduced lady beetles, pathogens, and parasites are thought to be causes for these declines. My hope is that here in Alaska we can learn from the impacts these factors have had elsewhere in the United States and prevent the same demise to our own two-spotted lady beetles.

The following is a list of lady beetle species known from Alaska (as of May 2023), based on specimen data and literature records cataloged by the University of Alaska Museum of the North Entomology Collection (available through the Arctos database). The species are organized by subfamily, and when available I added the species' common name in quotations.

FAMILY COCCINELLIDAE (“Lady beetles”)

Subfamily Chilocorinae
Brumoides septentrionis
Chilocorus stigma – “Twice-stabbed lady beetle”

Subfamily Coccidulinae
Coccidula lepida – “Snow lady beetle”

Subfamily Coccinellidae
Adalia bipunctata – “Two-spotted lady beetle”
Anatis mali – “Eye-spotted lady beetle”
Anisosticta bitriangularis – “Marsh lady beetle”
Anisosticta borealis
Calvia quatuordecimguttata – “Cream-spotted lady beetle”
Ceratomegilla ulkei
Coccinella californica – “California lady beetle”
Coccinella fulgida – “Gleaming lady beetle”
Coccinella hieroglyphica – “Hieroglyphic lady beetle”
Coccinella johnsoni (considered by some to be a subspecies of C. californica)
Coccinella monticola – “Mountain lady beetle”
Coccinella transversoguttata – “Transverse lady beetle”
Coccinella trifasciata – “Three-banded lady beetle”
Hippodamia americana – “American lady beetle”
Hippodamia arctica
Hippodamia expurgata – “Expurgate lady beetle”
Hippodamia falcigera – “Sickle-marked lady beetle”
Hippodamia parenthesis – “Parenthesis lady beetle”
Hippodamia quinquesignata – “Five-spotted lady beetle”
Hippodamia sinuata – “Sinuate lady beetle”
Hippodamia washingtoni - “Washington’s lady beetle” – please collect this species if you see it and send to the University of Alaska Museum, this species has been identified on iNaturalist however no specimens have yet been included in the statewide insect collection at UAM. Information on submitting specimens can be found here: https://www.uaf.edu/museum/collections/ento/donations/
Hippodamia tredecimpunctata – “Thirteen-spotted lady beetle”
Macronaemia episcopalis – “Episcopal lady beetle”
Mulsantina hudsonica – “Hudsonian lady beetle”
Myzia pullata – “Streaked lady beetle”
Psyllobora vigintimaculata – “Twenty-spotted lady beetle”

Subfamily Scymninae
Didion punctatum
Nephus georgei – “George’s lady beetle”
Nephus ornatus – “Ornate lady beetle”

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NON-NATIVE SPECIES (may be found in the state but arrived through human introduction):
Coccinella septempunctata - "Seven-spotted lady beetle", introduced to North America from Europe, considered invasive in some states/provinces due to competition with key native species resulting in reduction of native lady beetle populations
Hippodamia convergens - "Convergent lady beetle", introduced in Alaska but native farther south in North America where it is wild-collected and sold commercially. It is unclear whether this species is established in Alaska, but even without establishment there are risks posed by continuing to introduce these lady beetles. The Xerces society has an article that describes some of the the risks of releasing these commercially collected beetles even in areas where the species is native: https://xerces.org/sites/default/files/2018-07/18-018_01Xerces%20Soceity%20Lady%20beelte%20Release%20Statement.pdf