Random Plant: Wild cucumber revisited again

Fruit of a wild cucumber (Echinocystis lobata, Cucurbitaceae), photographed 10/23/2011 near Blissfield Michigan.

Last October I wrote about some wild cucumbers (Echinocystis lobata, Cucurbitaceae) that I found here in a southeast Michigan floodplain forest.  This past October I found them again in the same place, and took advantage of better lighting to get some better pictures of the fruit.  In the photo above the one on the left was the least mature.  It was a fully-developed, green spiny fruit, but hadn’t yet opened.  The one in the lower right was farther along.  You can see how the bottom peeled open to eject the seeds.  The one in the upper right was farther along still.  It had finished releasing its seeds and had turned brown.

Fruit of a wild cucumber (Echinocystis lobata, Cucurbitaceae), photographed 10/23/2011 near Blissfield Michigan.

This photo is a better close-up of a mature, unopened fruit.  These plants grow across most of North America, and if you happen to stumble across one in the autumn they really get your attention. Even in the summer before they fruit, you can recognize them by their somewhat distinct leaves and twining, viney growth.

Plant-Insect Interaction: Parasitoid wasps on goldenrod

Parasitoid wasps (Hymenoptera: Ichneumonidae: Tersilochinae) on goldenrod (Solidago sp., Asteraceae) photographed 11/02/2011 near Clayton Michigan.

This late into autumn most goldenrods (Solidago sp., Asteraceae) have dried up and gone to seed.  Last week, however, I found a few small plants in a meadow that still had handfuls of bright yellow nectar-laden flowers.  Upon closer inspection I realized I wasn’t the only one to take notice; the flowers were covered with dozens of these tiny parasitoid wasps (Hymenoptera: Ichneumonidae: Tersilochinae).

Parasitoid wasps (Hymenoptera: Ichneumonidae: Tersilochinae) on goldenrod (Solidago sp., Asteraceae) photographed 11/02/2011 near Clayton Michigan.

With winter fast approaching, it seemed unsurprising that so many of these wasps were crowding around some of the last few sources of nectar.  The individuals shown here spent most of their time with their faces buried in the flowers, lapping up the sugary food.  They emerged only briefly to move from one flower to the next.

Parasitoid wasps (Hymenoptera: Ichneumonidae: Tersilochinae) on goldenrod (Solidago sp., Asteraceae) photographed 11/02/2011 near Clayton Michigan.

Although adults of this subfamily feed on nectar, the larvae are internal parasitoids, predominantly of beetles (Triplehorn and Johnson 2005).   A female uses her long, slender ovipositor to lay an egg inside an active host insect. The egg hatches, the larva feeds on the host’s insides, and then eventually emerges as an adult, killing the host.  Some species of these wasps target beetles that are pests of crops and trees.  Tersilochus conotracheli is a parasitoid of the plum curculio (Coleoptera:  Curculionidae:  Conotrachelus nenuphar), a significant pest of fruit trees (Triplehorn and Johnson 2005).

Literature cited:

Triplehorn, C.A. and N.F. Johnson.  2005.  Borror and DeLong’s Introduction to the Study of Insects.  Seventh Edition.  Thomson Brooks/Cole, Belmont, CA.

Plant-Insect Interaction: Gall-making insect on giant ironweed

Giant ironweed (Vernonia gigantea, Asteraceae) photographed 10/23/2011 in a floodplain forest near Blissfield Michigan.

In the summer when giant ironweed (Vernonia gigantea, Asteraceae) is full of healthy nectar-laden blossoms, I’ve found it visited by silver-spotted skippers, cabbage whites, and other pollinating butterflies, bees, and wasps.  Now that we’re well into autumn, the dried, dead plants still host other insects.

Giant ironweed (Vernonia gigantea, Asteraceae) infested with an unknown gall-making insect. Photographed 10/23/2011 in a floodplain forest near Blissfield Michigan.

While out in a nearby floodplain forest here in southeast Michigan, I noticed a number of galls along the leaf midveins.  Naturally I split some open to find out what insect was responsible.

Unknown gall-making insect larva in a giant ironweed (Vernonia gigantea, Asteraceae). Photographed 10/23/2011 in a floodplain forest near Blissfield Michigan.

I found the larvae of some unknown insect in the middle of the galls.  I’ve made some effort searching the literature on leaf galls, but I have yet to identify this insect.  At this point I suspect it’s a fly (order Diptera) and possibly a gall midge (family Cecidomyiidae).

Random Plant: Sulfur cinquefoil

Sulfur cinquefoil (Potentilla recta, Rosaceae) photographed 10/23/2011 near Blissfield Michigan.

Introduced to North America from Eurasia, sulfur cinquefoil (Potentilla recta, Rosaceae) is an easy-to-identify member of the rose family.  It tends to grow in disturbed places, features palmately-compound leaves of five or (more commonly) seven toothy leaflets, has sulfur-colored flowers with five notched petals, and is generally quite hairy (Brandenburg 2010).

Sulfur cinquefoil (Potentilla recta, Rosaceae) photographed 10/23/2011 near Blissfield Michigan.

The distinct combination of characteristics make this often weedy plant stick out like a sore thumb.  I sometimes see it growing around driveways, buildings, and near field and forest margins. Although there are more well-behaved native cinquefoils, this more aggressive species is listed as a noxious weed in at least five states.

Literature cited:

Brandenburg, D.M.  2010.  National Wildlife Federation Field Guide to Wildflowers of North America.  Andrew Stewart Publishing, Inc., New York, NY.

Random Insect: Differential grasshopper revisited

Differential grasshopper (Orthoptera: Acrididae: Melanoplus differentialis) photographed 10/23/2011 near Blissfield Michigan.

After writing about differential grasshoppers (Orthoptera: Acrididae: Melanoplus differentialis) a few weeks ago, last week I noticed scores of them in a nearby soybean field.  I decided to get a closer look at one of them, and it responded by puking black fluid all over my fingers.  The fluid reminded me of used motor oil, and is apparently a defensive mechanism to deter predators.

Tiny common garter snake

Common garter snake (Squamata: Colubridae: Thamnophis sirtalis) photographed 11/02/2011 near Clayton Michigan.

I often come across common garter snakes (Squamata:  Colubridae:  Thamnophis sirtalis) here in southeast Michigan.  Today I was intrigued, however, by this particularly tiny individual.  I stuck a quarter next to his head for scale, and that seemed to arouse his suspicion as he cast a wary eye and flicked his tongue inquisitively.

Common garter snake (Squamata: Colubridae: Thamnophis sirtalis) photographed 11/02/2011 near Clayton Michigan.

These snakes breed in the spring and bear live young in the late summer, so this little guy must have been a juvenile.  He was only about 20 cm (7.9 inches) long, but full-grown adults reach 46 to 137 cm (18 to 54 inches) (Zimmerman 2002).

Common garter snake (Squamata: Colubridae: Thamnophis sirtalis) photographed 11/02/2011 near Clayton Michigan.

Although they usually have three bright yellow stripes running down their length, common garters are highly variable in coloration (Zimmerman 2002).  This snake exhibited a particularly drab, brown-tan coloration.  The typically bright stripes were a dull orange color on this individual.

This reptile was taking advantage of the early autumn sun heating some shale walkway stones for warmth.  With winter right around the corner, he was probably also looking for a warm cozy spot to overwinter.

Literature cited:

Zimmerman, R. 2002. Thamnophis sirtalis.  Animal Diversity Web.  University of Michigan Museum of Zoology.

Random Insect: Tarnished plant bug

Tarnished plant bug (Hemiptera: Miridae: Lygus lineolaris) photographed 10/30/2011 near Blissfield Michigan.

The plant bugs are the largest family of all the true bugs (Triplehorn and Johnson 2005).  Among the nearly 2000 North American species, one of the most common is the tarnished plant bug (Hemiptera: Miridae: Lygus lineolaris).  Highly successful as a generalist herbivore, these bugs are known to feed on the sap from over half the cultivated plant species in the United States (Capinera 2001).  It’s often a serious pest of commercial legumes, vegetables, and flowers (Triplehorn and Johnson 2005).

Tarnished plant bug (Hemiptera: Miridae: Lygus lineolaris) photographed 10/30/2011 near Blissfield Michigan.

I found this individual in a local greenhouse, basking in the warmth from the early autumn sun.  The greenhouse hosted various flower and vegetable plants earlier in the year.  In close proximity were both crop plants (especially soybeans) and a wide variety of trees in a mesic hardwood forest.  I can only imagine the smorgasbord this pest enjoyed throughout the year.  With winter fast approaching, this adult was probably looking for a comfortable spot to overwinter.

Literature cited:

Capinera, J.L.  2001.  Handbook of Vegetable Pests.  Academic Press, San Diego, CA.

Triplehorn, C.A. and N.F. Johnson.  2005.  Borror and DeLong’s Introduction to the Study of Insects.  Seventh Edition.  Thomson Brooks/Cole, Belmont, CA.