Monday, July 15, 2013

Lady Beetles. Not all are Welcome in the Garden

Asiatic Lady Beetle (Harmonia axyridis).
It poses a threat to native ones and it is a nuisance
when it gathers in large numbers
in winter in human habitations
 As I discussed in Native Plants and Wildlife Gardens on July 7th, not all ladybugs or lady beetles are beneficial. Some have been introduced from other lands and create trouble for the native species. Moreover, the sale of lady beetles as biological controls deserves thorough examination. You may be spending money for nothing or, worse yet, doing harm rather than good (Ladybugs,Lady Beetles or Ladybird Beetles. How Good are They?)

Mexican bean beetle (Epilachna varivestis). Stephen Ausmus. USDA
 Here are a couple of lady beetles which will surprise you. Not all lady beetles feed on other insects. A few feed on plants and may even be pests. The Mexican bean beetle (Epilachna varivestis) is just as cute as some of the most beloved lady beetles. Sadly it feeds on beans, peas and other plants of the pea family. The only consolation is that it also likes to eat that dreadful Japanese invasive plant, Kudzu.

Alfalfa Lady Beetle (Subcoccinella vigintiquatuorpunctata)
Luis Miguel Bugallo Sánchez/ Wikicommons

I also want to mention another pretty one, the Alfalfa Lady Beetle (Subcoccinella vigintiquatuorpunctata). It was introduced from Asia and feeds on alfalfa and an assortment of plants, such as bouncing Bet and campion. 

Another introduced species
 Seven-spotted Lady Beetle (Coccinella septempunctata)

Thursday, July 11, 2013

Rainy Days Pollination Blues!

 Guest post by David L. Green, retired commercial bee keeper, former editor of small newspaper, teacher. You can visit his website and his blog

Partially pollinated cucumbers. © Dave Green, 2013

With seven inches of rain in five days, bees had very little time to work. They delivered enough pollen grains so that the cucumbers did not abort, but not enough to flesh them out.

The one at left is a total lack of fertilization of the seeds at one end - that meant that the flesh did not grow, and the cuke had a "tail." Three more are slightly better. The one at the bottom has few of the incipient seeds fertilized in the middle, giving a waist to the cuke. These poorly pollinated cukes grow slowly and quickly get tough, sometimes bitter, as well.

If bee populations are normal, this problem should straighten out when the weather is more suited to bee flight. If you get very many like this in good pollination weather, you have a shortage of bees, and may need to work on increasing bee populations or hand pollinate.

My garden is pollinated by a mix of bees, with the bulk of the workload carried by bumblebees and honey bees, but we also have green sweat bees, squash bees, digger (Anthophora) bees, tiny Ceratina bees, and leaf cutter bees doing some of that work.

To make a perfect cucumber, you need to get almost all of the incipient seeds fertilized. That requires two grains of pollen - one for the embryo and one for the seed coat, so each perfectly pollinated cuke represents several hundred grains of pollen delivered to the flower.

A lot of folks think that, if they see a bee in a flower, that pollination is accomplished. But it's not an on/off switch. It's a progressive thing. It takes many bee visits to deliver all the pollen needed for multi-seeded fruits.

Every year, more and more gardeners report the symptoms of lack of pollination in their gardens. The problem seems to be accelerating.

It represents one of our most urgent environmental problems - pollinator decline. Our bees are disappearing. Some of that is due to habitat loss; some due to monoculture and its feast or famine pattern of intense bloom, followed by barrenness; some is from new diseases and parasites; but the worst and most difficult problem to solve is the loss caused by pesticides.

When cotton blooms, bees focus on those nectar-rich blossoms, and drop by the millions when the cotton is sprayed. In July clover is in full bloom in the orchard floor, and more millions of bees die when the fruit is sprayed. Community mosquito sprays are supposed to be applied when bees are not working, but this time limit is very poorly observed, and many more bees are dropped from applications done when they are out. And many gardeners plaster Sevin dust all over their gardens without thought of the bees.

All four of these cases I mentioned are illegal applications, because the label directions forbid them, but label enforcement is rare and usually amounts to a slap on the wrist, if anything.

So, if we do not begin to protect our pollinators - we lose much of the vitamin C (fruits) in our diet. Food costs will rise; only the rich will be able to afford many of the most nutrient-rich foods we have. We are left with grains that do not need bees - but remember that "man shall not live by bread alone."

© Dave Green, 2013
Retired pollination contractor