Crawlies with Cri: Transverse lady beetle

This week’s crawly is a very special lady. Lady beetle, that is! Meet the transverse lady beetle (Coccinella transversoguttata).
With only a handful of sightings in Oregon you’d be lucky to spot her indeed. Numbers of transverse ladies are declining throughout most of their range, due in large part to the introduction of non-native species such as the multicolored Asian lady beetle and the seven-spotted lady beetle.
Transverse ladies are named for their black elytra (wing cover) marking closest to their heads. While our pictured lady has a black dot, most transverse have an oblong black line laying “transversely” across the top of the elytra.
While they can be found throughout North America, most transverse lady beetles are found in the Rockies, Sierras and the Cascades. This pretty lady was enjoying the bounty of aphids to be found in Huckleberry Gap.
Transverse lady beetles are habitat generalists. This means they can live in a variety of different habitats, including agricultural areas, urban settings, coniferous and deciduous forests and grasslands/meadows. If their habitat runs low on food resources, they fly to a new habitat with more readily available meals.
Like all lady beetles, transverse chow down on aphids as well as other soft-bodied arthropods and their eggs such as spider mites, alfalfa weevils, leafhoppers and scale insects.
Transverse ladies are most active in May through September. Females will have one or two broods during this time, depending on weather and food availability. One female can lay up to 267 eggs in her (relatively) short lifetime.
Females will lay their eggs in small clusters on plants which have plenty of aphids on them, so the young larvae won’t have to go looking for a buffet. However, just in case the aphids are eaten by another arthropod, the females will also lay some unfertilized eggs in with the fertilized ones as a backup meal.
It takes about 20 days for the eggs to go through their larval and pupal stages before becoming winged adults. Ladies born in the fall will find a cozy spot to overwinter as adults and get the jump on the first aphids of the following spring.
Fun fact: Transverse ladies do well in alpine and subalpine regions because they are tough little beetles. Prior to their decline, they were distributed widely throughout the northern hemisphere, including populations in Greenland.
In addition to North America, their current native range includes Europe, Asia (except China) and Central America. They are well traveled ladies.
If you would like to see a transverse lady someday, help a girl out by not buying those bags o’ ladybeetles for pest control. Generally, those pre-packaged beetles are non-native and will only add to the stress on our native species. Moreover, while they’ll chomp down some aphids in your yard, they’ll quickly disperse as most yards just can’t provide enough food for that many beetles over any period of time.
Keep your yard pollinator friendly (lady beetles pollinate too!) and you’ll woo just the right combination of beneficial insects as well as birds and other fab crawlies.