northeast-flora-and-fauna

Last April along the Raritan River Greenway I saw a bunch of bugs on some of the greenery [1]. And while "bug" is sometimes used to refer to pretty much any arthropod from lobsters to millipedes to ants, I'm talking about the true bugs when I say this [2]. Being black and reddish orange bugs, they look a little like the milkweed bugs ( Large , Small , and False ), these Eastern Boxelder Bugs skew much more black than orange than you'll see with the milkweed bugs. Though I don't think their Western Boxelder Bug cousins live around here, they can be differentiated by the red veins on the otherwise black wings of the westerners.  These bugs can congregate together conspicuously because they smell and taste bad, keeping them safe from abundant predators like birds. They're another example of aposematism , where their black/orange color is an eye-catching signal that these guys taste bad. Their named after their favorite tree to feed on, Boxelder trees. They...

I've shown Large Milkweed Bugs before , though usually they were single individuals or small groups. But it's not usual to see a sizeable number of these bugs together, like in the picture below. I'm not exactly sure why this happens. I'm told that females usually lay around 30 eggs on/near a milkweed's seed pods; perhaps more than 1 female laid eggs near here. Or maybe this seed pod is a social hub where a maturing Large Milkweed Bug can find romance. This picture was from mid-September; I'm not sure if they mate that late in the season, or if they delay breeding until after migration. Yes, these guys migrate! While they enjoy eating our milkweeds and our summer temperatures, they wouldn't survive our winters. They migrate south in the winter and then start spreading north in the spring, much like some bird species, presumably lagging a little behind the new growth of milkweed plants that time of year. (You don't want to migrate ahead of your food sour...

Here are 2 related and similar-looking bugs I met on the same day, the Small Milkweed Bug and the False Milkweed Bug. Along with the Large Milkweed Bug, their relationship to a milkweed diet covers the full spectrum: The False Milkweed Bug (probably) never eats milkweeds/dogbanes. The Small Milkweed Bug sometimes eats milkweed but also eats other things outside the dogbane family of plants. The Large Milkweed Bug pretty much eats milkweeds and a few milkweed relatives in the dogbane family. I've talked before about the 2 theories on how the False Milkweed Bug developed its look and diet . First here's the Small Milkweed Bug, which has a red X with a black heart-like shape on the top (or the bottom, if the bug is upside down like in my picture). Note it's also on a milkweed seed pod, a not uncommon place to see these bugs. July 28, 2021 at the Sourland Mountain Preserve Photo 148654497, (c) jpviolette, some rights reserved (CC BY-NC) The next picture is of a False Milkwee...

Meet a Small Milkweed Bug . Although I've talked about them a little in a post about the similar-looking False Milkweed Bug, it doesn't look like I've showed a picture of the Small Milkweed Bug. This is yet another example of insect aposematism , where their red coloring signals to potential predators that these bugs are poisonous. Presumably they acquire their poisonousness in the same way that Monarch butterflies, Large Milkweed Bugs, and Red Milkweed Beetles acquire theirs - they get it by eating poisonous milkweed plants. There's a lot to compare and contrast with the Small Milkweed Bug and their Large Milkweed Bug cousins. Though both love to eat the seed pods of milkweed plants, the SMB has been known to feed on other plants and to actually eat some insects on occasion (including Monarchs). And while LMBs have a migration strategy based on following the milkweed crops, the SMBs can overwinter as (dormant) adults. July 10, 2021 at Duke Farms Photo 148186194, (c) ...

Here's a False Milkweed Bug I met a couple months back.  These guys have aposematic coloring but in their case it's misleading. As insects without a strong physical defense and that's not poisonous, they are advertising that they're dangerous to eat even though they're not. What they do have going for them is they look like (and are actually related to) the poisonous Large Milkweed Bug (a very common bug around me) and the Small Milkweed Bug (which is less common but looks even more similar to the False Milkweed Bug). This is called Batesian mimicry , basically impersonation a dangerous species when you're not dangerous. I don't think False Milkweed Bugs have been studied enough to know why they look the way they do. Did they evolve their red coloring so they'd look like their poisonous cousins? Or did their ancestors eat milkweed, develop their red coloring, and then evolve to eat a non-milkweed diet? Interestingly the Large Milkweed Bug eats exclusiv...

Meet a Swamp Milkweed Leaf Beetle !  When I saw this beetle, my first thought was that this was some sort of ladybug; aphids love eating milkweed, and ladybugs love eating aphids. Of course, I didn't see aphids on this milkweed, but I just chalked it up to a ladybug that was performing due diligence, making sure this milkweed didn't have a meal. But apparently this is a completely different type of beetle, one that eats the milkweed plant itself. Though their most frequently used common name seems to imply they exclusively feed on Swamp Milkweed, they will actually eat most (all?) of our milkweeds, and their second most frequently used common name is actually the broader Milkweed Leaf Beetle. Though they have a different look, they're related to another eater of poisonous plants, the Dogbane Leaf Beetle . Note the red coloring. As an eater of a poisonous plants, this beetle is trying to advertise to predators that it too is poisonous. This is known as aposematism . Milkweed...

Here's a False Milkweed Bug . I previously mentioned these guys when I talked about the Large Milkweed Bug. Notice that this bug is not on a milkweed or a dogbane plant; this (combined with an insect that looks like the Large or Small Milkweed Bug ) is always a strong clue that this is a False Milkweed Bug. (It sounds like the Large and Small Milkweed Bugs will occasionally use non-milkweed and non-dogbane plants as a host when their preferred plants are scarce, but I haven't actually observed that happening.) These guys are taxonomically true and false. Though not a true milkweed bug, the False milkweed bug is a true bug , just like the Large and Small Milkweed Bugs. Regarding the False Milkweed Bug's similarity to the Large and Small Milkweed Bugs, I had always assumed they were a case of Batesian mimicry , where a harmless species has evolved to look similar to poisonous species. It sounds, however, that we haven't ruled out that the False Milkweed Bug might have evo...

Here’s a Large Milkweed Bug I met. Around me, this is probably the most common milkweed-eating insect other than aphids (and the aphids are so small you might mistake them for a rust or other fungus). They can be confused with the Small Milkweed Bug or the False Milkweed Bug . Both lack the straight black bar across the top of its wings, and the latter isn’t found on milkweeds (which are poisonous to many animals). Note the orange/red on these bugs. Like Monarch butterflies, these insects eat the poisonous milkweeds and obtain a certain amount of poisonous protection for themselves. And the distinctive red coloring signals to predators that these guys aren’t good to eat. (Of course, sometimes orange/red coloring is a fake. AFAIK the False Milkweed Bug is safe to eat, and benefit from Batesian mimicry .)