The next slug to make your acquaintance is the Red-crossed Button Slug. This species is quite similar to one or two others as both larvae and adult, but given that most lists I have seen from Missouri list this one and not the others, I am pretty confident in this ID. This species lacks the stinging, protective hairs, going instead with a more camouflage approach of looking like a bit of leaf blight as it passes over leaves of oaks, hickories and quite a few other known woody, deciduous host plants.
The image above gives a glimpse into how the slugs get around – on a substance described as liquid silk. See the winding trails?
Here I caught one in the act. From what I’ve read, slugs leave distinctively shaped (indented) frass that is different from that of other caterpillars. I didn’t pause long enough to investigate.
Finally, the adult slug moth is pictured above. Slug moths are strongly attracted to lights and, from what I have read, are often some of the first species to show up when setting up a light and sheet/trap. I have a theory that this may be why I find many less slug caterpillars the closer I look near St. Louis. Although I found very similar habitats with the same composition and numbers of sapling oaks and hickories (the favored host plants), the closer I came to the city the number of slug caterpillars dropped significantly. Perhaps the city lights are sucking in the adults before they are able to reproduce? Probably a too simplistic idea, but it is a trend I noticed. It could just as well be due to fragmented habitat and overall less habitat available the closer one gets to the city.
While searching for arthropod subjects to photograph on Steve’s property, we decided to check the compost/midden pile and found something completely unexpected.
These beetles were crazy to watch – super speedy while flipping their gold-tipped abdomens over their backs in display. These guys yield even more support to my contention that the vast majority of ideas used in the sci-fi genre (particularly the creature-features) were taken from somewhere within the natural world.
This tiny and speedy ichneumon wasp, which I am calling a Theronia species, has been hanging around my patch of wild strawberries for a couple of months. If I am close to correct in the identification (with more than 100,000 described ichneumons, how close could I be?), then this species parasitize tent caterpillars along with a number of other lepidopterans.
“I cannot persuade myself that a beneficent & omnipotent God would have designedly created the Ichneumonidæ with the express intention of their feeding within the living bodies of caterpillars …”
I was thrilled when I took my camera inside from shooting in my wildflower garden on a past summer day and identified this hymenopteran as a Bee Wolf. Philanthus gibbosus (Family Crabonidae) is what I am calling this one. Bee Wolves get their name from doing what you expect, feeding primarily on bees. These solitary wasps will load their brood chambers with pretty much any bee or wasp smaller than themselves that they can catch as a provision for a single egg they deposit prior to sealing the chamber shut. Some taxa have specific bees they prefer to catch and this can aid in identification. This poor thing was quite beaten up as you can see in the photograph below. Missing a few legs, it probably escaped a bird or larger insect, and was not happy to have me and my camera in its face. In the photo above I captured it doing a rapid vibration of its wings, something I read that these guys are known for doing as a communication. I can’t imagine what she may have been trying to tell me…
I believe the insect below to also be a species of Bee Wolf, but have not yet been able to put a name with this one. I photographed this one having a drink in a wet area of Shaw Nature Reserve early one morning.
The False Milkweed Bug (Lygaeus turcicus) is a seed bug that, although quite similar in appearance to the Small Milkweed Bug (Lygaeus kalmii), is not strongly associated with milkweed.
As can be seen in the photograph above, the False Milkweed Bug is most often found feeding on yellow composites (Family Asteraceae). These bugs were all photographed at Shaw Nature Reserve on what seems to be this insect species’ favorite food plant, the False Sunflower (Heliopsis helianthoides).
There are several members of the Lygaeidae family that are aposematically colored and found in North American prairies. As mentioned, it seems that the False Milkweed Bug does not typically utilize milkweeds. The Small Milkweed Bug feeds on milkweeds as well as other plant taxa. The Large Milkweed Bug feeds exclusively on milkweed. There is obviously a great case of Mullerian mimicry (distasteful organisms appearing similar to one another to benefit from a an easily identified color or body type) going on here, but it gets pretty complicated.
What has happened to the False Milkweed Bug? Is this a case of a species that once fed primarily on milkweed and developed aposematic coloration but has since switched food preference? Or, is this a case of a palatable species mimicking (Batesian mimicry this time) the aposematic coloration of a truly noxious species? Thinking about this, it is easy to see the selective advantages that could result from either possibility.
First, a little background…
Some insects that feed on milkweed benefit by concentrating chemicals called cardiac glycosides that are toxic irritants to vertebrate predators. Cardiac glycosides are an irritant to vertebrate herbivores (livestock) and vertebrates that feed on insects that feed on milkweed and store these compounds in their tissues. However, they are not a significant problem for insects that feed on milkweeds – they simply pass through their guts (insects that store these specific toxins, for example the monarch, must have biochemical changes to avoid toxic effects). The milkweed’s primary defense against the seed bugs and other herbivorous insects is the milky sap that gets forcefully pumped from any mechanical damage that is inflicted on the plant. For this reason the milkweed is a pain for an insect to feed on.
For a seed bug, with its piercing-sucking mouth parts, feeding on the gummy sap of a milkweed is a significant hurdle. Assuming the False Milkweed Bug once fed from milkweed primarily and gave it up would be a significant advantage. Keeping the aposematic coloration, which would allow it to gain the benefit from its vile-tasting, similarly colored cousins, still feeding on milkweed, would be advantageous as well. With my brief observations, the False Milkweed Bug still behaves conspicuously – feeding and doing everything else it does out in the open, suggesting that the aposematic coloration is still working in this mimic-model system, whatever the source history ultimately may be.
I find the flies to be one of the more interesting groups of insects and I was constantly on the lookout for new species to photograph this summer. There is such diversity in the flies, from size to form and function. There is still so much to learn about some flies, including some rather common species that researchers have still not described where or on what the larval forms live. To start, here is a closeup of a true giant of the flies, a Robber Fly (Family Asilidae). The Robberflies are true predators, with an intimidating beak that they use to inject neurotoxic and protein-dissolving cocktails.
The photograph above showcases a fly that should be a favorite of gardeners and farmers. Flies in this family (Tachinidae) parasitize a number of different insects and this species specializes in many of the plant-feeding true bugs like Stink Bugs and Leaf-footed Bugs. The generic name can be translated from Greek to mean “hairy foot” and the specific name “pennipes” means feather. This namesake feature can be seen on the rear legs of this fly in the photograph above.
The Thick-headed Flies are extremely interesting and a joy to watch. These guys not only mimic bees and wasps, but they also parasitize the hymenoptera by depositing their eggs on the stinging insect, sometimes attacking the host to place their egg. The eggs hatch and the larvae become internal parasites of their host.
The minuscule Bee Flies in the genus Geron parasitize moth caterpillars. The adults of these flies feed almost exclusively on yellow-flowered Asteraceae.
Don’t be threatened by the sting-like structure that this Scorpionfly (Family Panorpidae) has arched over its back. This is simply the male genitalia and is quite harmless. Scorpionflies primarily make a living by scavenging on dead insects, and like many flies, exhibit elaborate behaviors to attract mates. These flies will perform various dances in front of females and will often provide a ripe insect carcass as a prenuptial gift.
Finally, here is a rather different view of a Greenbottle Fly. I hope this helps to describe some of the fascinating diversity in form, function and behavior that can be found within the Diptera. These are but just a few of the easier to find and photograph! I hope to continue my exploration of these fascinating insects next year.
I finally found a monarch caterpillar on one of my plants after a 3-4 year absence. Knowing the poor success rate when I had them in the yard in previous years, I decided to try my hand at rearing this one inside. I read a little on proper practices online and had received some advice from someone I work with (thanks Tim!) and watched as the little one put on the weight at the expense of my common milkweed I harvested from the garden. Unfortunately the idea for a time lapse project came too late and . I wasn’t prepared and wasn’t knowledgeable enough about the metamorphosis process. I tried my best. I made several mistakes and will hopefully remember these next time. I also had a couple of equipment failures that caused me to miss a couple of gaps many hours in length. Tim and his family have successfully reared and released a good number of monarchs this year and tag them for hopeful data points on the migratory routes (just like in birds). He had an extra tag and I tagged the little female prior to her release. Hopefully she will make it the ~1800 miles from central Missouri to central Mexico where she will overwinter before heading back north again next spring.
Even with the problems, I kind of like the outcome. I can’t wait to try again… 😉
Did you know that there is a primitive group of the hymenoptera with free-living larvae that look very much like the caterpillars of the lepidoptera? Known as the Sawfly, there are morphological distinctions between them and the caterpillars and they can also be distinguished by this defensive posture adapted by the Sawfly larvae (Arge sp.) pictured here.