![\"thistle](\"https:\/\/uwm.edu\/field-station\/wp-content\/uploads\/sites\/380\/2018\/07\/tortoise-btle-thistle18-24rz.jpg\")
<\/a><\/figure>\n\n\n\nThistle tortoise beetles are in the huge Leaf beetle family, Chrysomelidae (possibly 60,000 species worldwide), and in the Tortoise beetle subfamily Cassidinae (about 3000 species). They owe their tortoise-like appearance to flared edges of the head, thorax, and elytra (although unlike a tortoise, the front and rear ends of the \u201cshell\u201d aren\u2019t fused<\/a>). The beetle\u2019s shape allows it to squat right on the leaf\u2019s surface, which protects its underpinnings from ants, and because it melds seamlessly with the leaf, it\u2019s less likely to cast a shadow for predators to see.<\/p>\n\n\n\n Some tortoise beetles are brilliantly-colored https:\/\/en.wikipedia.org\/wiki\/Imperial_tortoise_beetle#\/media\/File:Imperial_tortoise_beetle.jpg<\/a> and https:\/\/commons.wikimedia.org\/wiki\/File:Desmonota.variolosa.jpg<\/a> \u2013 so striking that, according to Brittanica.com, a few are used to make jewelry. Our native Golden tortoise beetle can change colors \u2013 not through a trick of physics, like the Dogbane leaf beetle of previous BOTW fame<\/a>, but intentionally (\u201cemotionally\u201d): https:\/\/blogs.scientificamerican.com\/running-ponies\/glad-you-ditched-the-anal-fork-golden-tortoise-beetle\/<\/a>.<\/p>\n\n\n\n Chrysomelids are vegetarians – some specializing on just a few plant species, and some considered agricultural pests.<\/p>\n\n\n\n The aptly-named THISTLE TORTOISE BEETLE<\/strong> (Cassida rubiginosa<\/em>) is also called the Green thistle beetle and the Thistle-defoliating beetle. And the Bloody-nosed beetle – according to bugguide.net<\/a>, the Latin rubiginosus<\/em> means \u201crusty\/rust-colored\u201d and \u201crefers to the beetle’s ability to secrete a reddish liquid from its head\u201d (a phrase that was repeated verbatim in lots of sources but elaborated on by none of them. A defensive cocktail?). The spines that poke out from around the larval body are called \u201cscoli\u201d and are sensory organs – like the bumpers on a bumper car, they tell the larva when something brushes against it (which makes the larva hunker down on the leaf surface).<\/p>\n\n\n\n Thistle tortoise beetles are not native to these parts. In the Old Country, they are found throughout the Continent and across northern Russia. They were first observed in Quebec in 1901, and they spread out from there and are now ensconced in grasslands, Ag lands, and disturbed\/neglected open areas across the northern part of North America (and they were intentionally introduced to Virginia).<\/p>\n\n\n\n With a few (major) exceptions, their story is similar to that of many other leaf beetles. A female deposits her eggs, about three at a time. In this case, they are placed on the undersides of leaves in small packets<\/a> called o\u00f6thecae<\/em>. She takes her time, ovipositing in fits and starts with sizeable time-outs in between, for a total of up to 1,000 eggs. Before she walks away from each egg packet, she covers it with a \u201csecretion\u201d and smears feces over it, which discourages predators and increases the eggs\u2019 chances of hatching.<\/p>\n\n\n\n There is one generation a year, but because the adults overwinter in soil or leaf litter and emerge in spring, and because a female may lay eggs for three months or more, and because the larvae pupate and emerge as adults the same summer and keep on eating until it\u2019s time to tuck in for the winter (they eat knapweed and burdock, too), you can find adults and larvae abroad for much of the growing season. Adult feeding is superficial but the leaf-skeletonizing larvae really dig in; the \u201cwindow pane\u201d appearance of the leaf is characteristic.<\/p>\n\n\n\n Here\u2019s a pupal case \u2013 https:\/\/bugguide.net\/node\/view\/960322\/bgimage<\/a> – a number of the pupal cases that the BugLady photographed were broken open at the front, where the adult had emerged.<\/p>\n\n\n\n Canada thistles aren\u2019t from these parts, either, but they\u2019ve lived here since the 1600\u2019s. Like the beetle, Canada thistle is native to northern Asia and Europe (it\u2019s called Creeping thistle in England), so in this case, both the pest plant and one of its grazers have accidentally made it to our shores. Thistle tortoise beetles are crazy about Canada thistles and have been introduced as a biological control in New Zealand, a country that is extremely cautious about opening its borders to exotic plants and animals (in New Zealand they call it California thistle).<\/p>\n\n\n\n Can you order up a bushel of them to take care of your Canada thistles? You cannot. Says the Integrated Weed Control Project at Washington State University, \u201cThis insect is known to attack native thistles, is not an approved agent, and is NOT distributed by IWCP.\u201d For a couple of \u201cshout-outs\u201d for native thistles, see https:\/\/xerces.org\/wp-content\/uploads\/2016\/10\/2016-029_Native-Thistle-Conservation-Guidelines_FINAL_web.pdf<\/a> and https:\/\/weedwise.conservationdistrict.org\/2017\/thistle-identification.html<\/a>.<\/p>\n\n\n\n Interesting Tortoise Beetle Fact #1:<\/strong> What is that dark, dampish glob, anyway?<\/p>\n\n\n\n Apparently, the larva never throws anything away. Instead of dropping off each time the larva molts, the old skin is stored on twin forks protruding from its aft section. And each time it poops, the frass (bug poop) is also conserved on those caudal\/anal forks. So \u2013 skin-frass-frass-frass, skin-frass-frass-frass \u2013 repeat as necessary – the compressed and portable scrapbook of its life https:\/\/bugguide.net\/node\/view\/1238110\/bgimage<\/a> and https:\/\/bugguide.net\/node\/view\/249152\/bgimage<\/a>.<\/p>\n\n\n\n Why? The “stercoraceous parasol<\/em>” (1869), \u201cfaeces pack\u201d<\/em> (1915), \u201cfrass mask<\/em>\u201d (1935) or \u201cfecal shield<\/em>\u201d (today) has long intrigued naturalists. An early theory about it being a tiny umbrella has been rejected. It effectively disguises its bearer as an inanimate blob of bug droppings, and many predators avoid droppings because they are unsanitary health risks. Add to that the fact that some species of tortoise beetles eat plants that are chemically defended, and so are toxic. And, add to that the fact that the larvae can wave the mass of stuff around in a threatening manner, as several did while the BugLady was photographing them. It\u2019s not foolproof \u2013 spiders and some insects like stinkbugs and damsel bugs can pierce it.<\/p>\n\n\n\n Interesting Tortoise Beetle Fact #2:<\/strong> And it\u2019s a lot to digest!<\/p>\n\n\n\n Humans can\u2019t digest cellulose, the main structural ingredient of a plant cell wall, because we lack the necessary enzymes to do so (and so it travels through our systems as roughage). Some herbivores produce the necessary enzymes, and others outsource the job to micro-organisms like bacteria. The Thistle tortoise beetle has developed quite a complex process.<\/p>\n\n\n\n It has the enzymes needed to digest cellulose but lacks the ability to break down another important component of a plant cell wall \u2013 pectin. But \u2013 it hosts free-living bacteria that are found in special sacs in the beetle\u2019s gut, bacteria that provide enzymes that the beetle uses to break down pectin. With the help of the bacteria, the beetles can access the nutrients in plant cells; within the shelter of the beetle, the bacteria can afford to simplify and streamline its genome. Win-Win. https:\/\/www.sciencedaily.com\/releases\/2017\/11\/171116132757.htm<\/a>. Mom passes the bacteria along by applying a coating to the cap of each egg shell, which the larvae eat after hatching.<\/p>\n\n\n\n Interesting Tortoise Beetle Fact #3:<\/strong> Medical devices R US<\/p>\n\n\n\n Hmmm \u2013 how to explain this delicately so that the corporate filters don\u2019t block this episode. OK \u2013 the female\u2019s reproductive system is a long and winding road, and the male has adapted quite adequately. So well, in fact, that your next catheter may be modeled on the organs of the Thistle tortoise beetle. The popular press was all over it.<\/a><\/p>\n\n\n\n![\"thistle](\"https:\/\/uwm.edu\/field-station\/wp-content\/uploads\/sites\/380\/2018\/07\/tortoise-btle-thistle18-2rz.jpg\")
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![https:\/\/en.wikipedia.org\/wiki\/Imperial_tortoise_beetle#\/media\/File:Imperial_tortoise_beetle.jpg<\/a> and](\"https:\/\/en.wikipedia.org\/wiki\/Imperial_tortoise_beetle#\/media\/File:Imperial_tortoise_beetle.jpg\"){kind=link}
![https:\/\/commons.wikimedia.org\/wiki\/File:Desmonota.variolosa.jpg<\/a> \u2013 so striking that, according to Brittanica.com, a few are used to make jewelry. Our native Golden tortoise beetle can change colors \u2013 not through a trick of physics, like the](\"https:\/\/commons.wikimedia.org\/wiki\/File:Desmonota.variolosa.jpg\"){kind=link}