Insects

July - a time of transition in the garden

July always feels like a time of transition in the garden. The summer squashes, tomatoes and peppers have begun producing, the spring peas, potatoes and garlic are coming out and the fall brassicas, beans and turnips are going in.

Quite a few of the garden beds are transitioning from one crop to another: peas to pole beans, garlic to turnips, fava beans to cauliflower, potatoes to broccoli, and onions to salad turnips.

There are also succession plantings of the same crop in some garden beds: fall carrots have been seeded between the rows of spring carrots and bok choi has been replanted between the few remaining spring plants.

The least appealing aspect of this time of year is doing battle with the mid-season diseases and pests. Squash vine borers have made their appearance, along with the first signs of mildew.

And this year's drought has increased the wildlife damage to our tomatoes and eggplants. We seriously need some rain!

 

A Surprise Treasure in our Garden!

While topping the Brussels sprouts* on Wednesday evening, I happened upon an odd, exotic-looking object that was attached to the main stem of one of our plants.  It looked like something that would fit right in on the set of the movie Alien!  However, as I examined it more closely, I realized that it is something that is very good to find in one's garden -- that is, an ootheca, (i.e., egg case), from a mantid!  In our case, (no pun intended!), based on its size and shape, this egg case is from a Chinese mantid (Tenodera aridifolia sinensis). 

 

Ootheca (egg case) from a Chinese mantid, on a Brussels Sprout Plant

[photo - Susan Doctrow]

The Chinese mantid is the world's largest mantid, often reaching over four inches in length when fully grown.  They are brown, with green or yellow stripes on the sides of their wings, and they are widely sold through garden catalogs and garden centers because they are carnivorous predators that will often feed on other insects and creatures that are garden pests.

See our earlier post for a photo of the adult Chinese mantid that we discovered on our pole bean trellis:

http://www.robbinsfarmgarden.org/content/day-garden-september-8-2012

Here's a Chinese mantid creating an egg case: 

http://www.youtube.com/watch?v=AyrQSfXiGQY&feature=fvsr

And here's a mantid egg case actually hatching: 

http://www.youtube.com/watch?v=fJoNzO0iNVQ

---------------------------------------------------------------------------------------------------------------------------

*  We learned, this season, that topping Brussels sprouts and flower sprouts when they are 3-4 weeks from harvest leads to bigger, more-consistently sized sprouts at harvest time.

 

Carrots: Lessons Learned This Year

carrotsThis year's early-season carrots struggled through an infestation of Asiatic Garden Beetles, a nocturnal garden pest that needed to be painstakingly removed from the soil during thinning and weeding. The early crop took a bit longer than expected to mature, but the beetle-busting efforts paid off with truly lovely carrots.

When our late-season carrots got off to a rocky start, we began to worry. We seeded an area vacated by fava beans on July 7th. Germination was good, the seedlings began growing, but then they all died. All except a few that had been in the shade of the mature carrots at the ends of the rows. We're not certain, but it may be that the seedlings became too dry at a critical period and quickly withered in the mid-July sun. They were replanted and the second carrot crop now appears to be on its way to greatness. But for my part, I'd like to document a few carrot lessons we've learned this year.

1. Favor varieties with short growing seasons. Two crops divides the season into mid-April to mid-July and mid-July to mid-October, giving a generous 91 days for maturity. Yet, carrots grown in the peripheries of the season take longer than the predicted 75 days.

2. Plant the rows close together. The carrots shared a bed with salad turnips this year, dividing one 6' x 9' planting bed into two beds 3' wide. We planted five rows 6 inches apart and the spacing was excellent.

3. Sow plenty of seed. Carrots take their time germinating (1-3 weeks), so they don't allow much opportunity to infill seed bare spots without paying a heavy price in lost time.

4. Keep the newly-seeded soil moist. We used shade cloth after re-seeding in July and left it in place until the seedlings had a good roothold (at about 2" tall). This may be less of a problem for the early crop.

5. Lightly thin the seedlings each week. Successive thinning doesn't take long, and it results in the best seedlings surviving to maturity at the ideal spacing of around 1 inch apart.

Another Beneficial Insect Spotted at Robbins Farm Garden!

Locust Borer BeetleOn Saturday, September 8, 2012, I spotted this unusual insect gathering nectar from our garlic chive blossoms.   At first glance I thought it was some kind of wasp, but upon closer inspection, I decided that it was some kind of beetle.  (This type of visual imitation, by the way, is called biomimicry.  In this specific case, this beetle evolved to resemble a wasp as a deterrent to possible predators.)  After some online research, I discovered that what we had here is a Megacyllene robiniae  --aka a Locust Borer Beetle.  [Photo credit – Alan Jones].

This convincingly camouflaged beetle shouldn't be a problem in our garden, as this native insect only lays its eggs on, and then subsequently damages, black locust trees.  It was on the chive blossoms simply to feed, and, coincidentally, to pollinate.  So, as far as we are concerned, this is another beneficial insect helping to tend our garden!

For more info on this insect, see http://www.cirrusimage.com/beetles_locust_borer.htm

 

This Day in the Garden - September 8, 2012

Our first harvest of sweet potatoes, leeks and rhubarb, and the last of the watermelons. None of the watermelons this year have made it out of the park - it's just too much fun to share them on the spot. Those eight big sweet potatoes were from just one plant! We'll wait a few weeks to dig the rest, after the plants start dieing back.

Michael spotted a special visitor on the pole beans:  Our mantid friend is a Tenodera aridifolis sinensis, aka a Chinese Praying Mantis.

See http://speciesofjabin.blogspot.com/2010/08/savanna-chinese-praying-mantis.html

A praying mantis is a voracious predator, (i.e., a "beneficial" insect), and its favorite munchies are insect & bug pests that we don't want in our gardens!  Isn't it nice to know that Mother Nature is helping us out?  (And kudos to Alan for the excellent click!)

Praying Mantis

Hornworm returns

HornwormSphinx moth

A sphinx moth has dropped by the garden once again. That's the parent of the hornworm caterpillar Lisa found munching last week on one of our green tomatoes.

The hornworm looks like something out of a medieval fairytale. It's bright green with slanted white stripes and dark eye-spots on its sides and a curved black horn extending out from its rear end.

Because their coloring is so close to that of the plants they visit, hornworms can be hard to spot at first, clinging as they do to the underside of the branches they defoliate. But once you see one, you think you're looking at a miniature monster.

A hornworm brigade attacked our tomatoes two summers ago. Fortunately, however, right behind them came a flight of parasitic wasps launching a counterattack of their own. They stopped most of the hornworms in their tracks, but not before the little monsters had stripped bare the tops of several tomato plants.

So far this summer, we've spotted just one horn worm, and no parasitic wasps.

Curiously enough, this time the hornworm did not go for the tomato plant's leaves. This time Lisa found him munching on a tomato.

 

Spined Soldier Bug on Patrol in the Robbins Farm Garden!

On Saturday morning, July 14th, I discovered this 1/4-inch long, light-orange colored bug on the basil.  It proved difficult to photograph, since it really didn't like to stand still.  However Alan, being very patient, finally captured these two shots -- one for close-up detail, and the other with my hand for scale.

   

After many hours of searching the internet, I am now convinced that what I found is the nymph stage of a type of Stink Bug -- the Spined Soldier Bug, Podisus maculiventris.  While many types of Stink Bugs are exceedingly damaging to many food crops in the U.S., this particular bug is actually beneficial because it's a predator.  It kills other insects by literally sucking the life out of them!  

So, this is one of the good guys!  It's a good thing that we don't need to get rid of this bug, as stink bugs are very difficult to control, both organically and conventionally!

 

 

For more info on Spined Soldier Bugs:
1.  http://www.uky.edu/Ag/CritterFiles/casefile/insects/bugs/stinkbugs/stinkbugs.htm#nymph

2.  http://www.whatsthatbug.com/2010/08/02/immature-predatory-stink-bug-eats-monarch-caterpillar/

3.  http://bugguide.net/node/view/237854

4.  http://stinkbugsguide.net/infestation.htm

5.  http://www.motherearthnews.com/blogs/blog.aspx?id=142346&LangType=1033&blogid=1502

 

Stars for the Bees

A newcomer this year to our herb garden is unexpectedly boisterous and intriguing: The herb borage joined one of our two herb beds at the end of April, when we redug and redesigned them. It's already a hearty bush, about three feet tall and right now in heavy bloom. Known also as "starflower", its blooms appear on the plant in both blue and pink versions--apparently younger and older flowers. The honey bees are enjoying the plant immensely; the plant is known for producing good honey, and we're always happy to see pollinators in the garden. We're just learning about borage, since it isn't commonly found in North American herb gardens. It's a probable native of North Africa that has spread across Europe, Asia Minor, the Mediterranean, and South America. Borage is apparently easy to grow from seed, but we acquired our plant from Mahoney's; it's an annual that is said to reseed itself easily, so we won't need to shop for it next year.

We might have made more of the plant's role in companion planting, had we known: it repels tomato hornworms if planted with tomatoes--and cabbage worms when planted with brassicas (hurray!). The plant debris is also a helpful mulch; it contains high levels of calcium and potassium which help the setting of fruit for all fruits and vegetables.

The whole plant is edible, the leaves having a cucumber flavor (I can vouch for that, though the fuzziness of the leaves is a little odd on the tongue), the blooms somewhat honey-sweet; the flower is often used to decorate desserts as it is one of very few truly blue-colored edible substances. It can be used both as a fresh vegetable (in salads and soups) and as a dried herb (in tea).

Beyond its kitchen garden uses, the plant's seed oil is a rich source of gamma-linolenic acid (GLA), an omega-6 fatty acid found chiefly in vegetable oils. This fatty acid is found as a dietary supplement said to treat inflammation and auto-immune diseases like rheumatoid arthritis. Finally, borage is a traditional garnish in the Pimms Cup cocktail, the expected beverage at your neighborhood polo match or Wimbledon.

A quality we will not test, though it would have been timely on the 4th, is due to the plant containing nitrate of potash; when burned, the plant throws sparks with a tiny explosive sound.

Sources:

Grieve, M. (Maud) (1931). Borage. In A Modern Herbal. Retrieved from http://www.botanical.com/botanical/mgmh/b/borage66.html

Klein, Carol (2009, January 23). Star Turn. Retrieved July 9, 2012, from http://www.guardian.co.uk/lifeandstyle/2009/jan/24/carol-klein-borage

Borage. (2012, June 28). In Wikipedia, The Free Encyclopedia. Retrieved23:31, July 9, 2012, from http://en.wikipedia.org/w/index.php?title=Borage&oldid=499739160

Biocontrol of Cucumber Beetle Larvae (an organic solution)

A living organism that can be used to control pests and/or diseases is called a "biocontrol."  The following web sites all sell (or have a list of sellers of) Heterorhabditis bacteriophora, a parasitic nematode (microscopic worm), that enters and destroys the larvae of the cucumber beetle.  It is effective against some other larvae, as well.

1.  http://greenmethods.com/site/shop/buy-bugs/3/
2.  http://www.fertilizeronline.com/nematodes.php
3.  http://www.bugladyconsulting.com/Suppliers%20of%20beneficial%20insects.htm

And for more info on insect parasitic (i.e., "beneficial") nematodes:  http://www.oardc.ohio-state.edu/nematodes/

Buying beneficial nematodes can be a bit pricey, especially for a smaller-sized garden, so you may want to try buying them and sharing the expense with other gardening neighbors, (which is always a good idea, anyway, since this helps to eliminate the pest from your entire neighborhood, not just your yard !), or you may want to try a different, less expensive solution first, e.g., the Burpee cucumber beetle trap.  However, these nematodes will eliminate some other pests besides the cucumber beetle, while the traps (I believe) are very target insect-specific.

Note:  Nematodes and other treatments that control the Striped Cucumber Beetle are equally effective against the Spotted Cucumber Beetle. 

Spotted Cucumber Beetle (adult)

 [See journal entry, below, for more info regarding the Cucumber Beetle.]

 

Striped Cucumber Beetle - Not Just a Problem with Cucumber Crops!

FYI, last week, while examining our potato crops, I found a 1/4-inch long, yellow and black striped beetle -- the Striped Cucumber Beetle -- on one of the leaves!  This chewing insect can devastate a crop if allowed to munch and reproduce unchecked.  Besides the obvious leaf damage that they do, (which compromises a plant's ability to photosynthesize, i.e., create food), these insects can oftentimes be vectors of plant diseases such as bacterial wilt and cucumber mosaic virus.  The adults feed on squash family plants, beans, corn, peas, and blossoms of many garden plants, often killing the plants.  Larvae feed on roots of squash family plants only, killing or stunting the plants.  Adults overwinter in dense grass or under leaves, emerging in early-spring to early-summer.  Eggs are layed at the base of target plants, and hatch in 10 days.  Larvae burrow into the soil to feed on roots for 2-6 weeks, pupate in mid- to late-summer into 1/2-inch, white grubs with brown heads, then, in 2 weeks, emerge as adults to feed on blossoms and maturing fruit.  One to two generations per year. 

NOTE:  Besides the adult beetle's description, the above information regarding the Striped Cucumber Beetle also applies to the Spotted Cucumber Beetle.  See above journal entry for photo of the Spotted Cucumber Beetle.

Striped Cucumber Beetle (adult)

For more info on the Cucumber Beetle, and to see a diagram of the Life Cycles of both the Striped and the Spotted Cucumber Beetles, click here.

To control:  Remove and destroy crop residues where adults overwinter.  Use floating row covers to protect seedlings and plants, and hand-pollinate (using cotton swabs) the squash family plants.  Pile salt marsh hay or straw deeply around plants to discourage beetle movement amongst plants.  Apply kaolin clay to uncovered plants, using special care to coat the undersides of leaves, too.  Reapply after rain.  Hand-pick or vacuum adults, and/or apply parasitic nematodes, (Heterorhabditis bacteriophora), weekly to soil to control the larvae.  If all else fails, pyrethrin (a plant-based insecticide), may be applied to beetles seen feeding on pollen in flowers.

 

Videos from the summer

I've been remiss in posting several brief videos I took this summer of animal activity in the garden. The first two are of the tremendous activity bees have kept up on the fennel plant. It probably won't translate well, but when I see these, I think of scenes from Bladerunner or Star Wars, in which huge vertical structures accept vehicle docking at multiple levels.

The third one is pretty hard to watch, entirely attributable to poor photography. It is a view of the compost pile, freshly turned by compost captain Stephen Lee.

 

Visitors, human and caterpillar

I opened the garden for a couple of hours in the afternoon and quite a few families came through.

Three Chinese-American boys became quite attached, staying over half an hour and wanting to eat various veggies. I gave them a few cherry tomatoes, and even a tomatillo. The older boy wanted to take home seeds and plant. Wait until spring I suggested. He may come Saturday, when I said we'd be there.

His father came by, not speaking English (Jerry is in the 4th grade at Brackett and is fluent). He found a caterpillar in the carrots.

On Butterflies and Caterpillars

We've recently discovered several brightly-striped caterpillars feeding on the carrots, fennel and parsley. At first, we assumed them to be Monarch butterfly (which are similarly striped), but this was questioned by an astute garden visitor (we're fortunate to have many).

 

Upon further investigation, we've identified the caterpillars as those of the Eastern Black Swallowtail (Papilio polyxenes) also called the American Swallowtail Butterfly. This butterfly's larvae feed on members of the carrot family: Dill, Fennel, Golden Alexanders, Parsley, Parsnips, Queen Anne's Lace and Carrots.

 

Squash Vine Borer

I noticed that some of the winter squash leaves were wilting.  To me, this is clearly an indication of the presence of a squash vine borer.  I gave it a couple days, and it was only getting worse.

 

In addition to the wilted leaves, we also appeared to have small holes in the vines near the base, and "yellow brown excrement".

To find the worm, I pressed along the main vine starting at the base until I found a soft spot (which was on the bottom of the vine).  I then used a knife to cut into this spot until I could spot a worm.  This is the larger worm I dug out of the squash vine.

Oh No!

 

Last week I found the first tomato hornworm of the season!  Last year they were a big problem- they grow insanely large and can quickly decimate the leaves of a tomato plant.  This one is just a baby, and looks just like an inchworm except for the horn.

 

Pages

Subscribe to RSS - Insects