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Extension Entomology

Month: May 2015

Ash/Lilac Borer Activity

Posted on by Sharon Schroll

—Dr. Robert Bauernfeind

Not to beat a dead horse given that Dr. Cloyd’s KIN #2 article addressed the facets of ALB development/damage/control, and last week’s update in KIN#3 substantiating the actual initiation of the 2015 flight activity, but I noted that the table was incorrect in the “Date” column. So to correct that, I have entered the proper dates, and also added in this week’s flight numbers. Again, as can be seen, these moths just don’t fly at temperatures below 70. So this week when temperatures were into the 70’s, moths were active. And, no more wrens.

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Brownheaded Ash Sawfly (BHAS) Update

Posted on by Sharon Schroll

—Dr. Robert Bauernfeind

While I had not intended to follow the progress of BHAS as I have done in previous years, I can’t seem to drive past the “busy beavers” without stopping to have a look. And so, within the past week, pinhole feeding has progressed to the tattered-appearance phase. Like ETC and EPS, BHAS activities are about a week ahead of where they were in 2014.

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Caterpillars and Sawflies

Posted on by Sharon Schroll

—Dr. Raymond Cloyd

Caterpillars are the larval stage of butterflies and moths; whereas the larval stage of sawflies is greasy looking and slug-like with the adults resembling wasps. Remember, caterpillars are in the insect order Lepidoptera (butterflies and moths) whereas sawflies are in the order Hymenoptera (ants, bees, and wasps). There are a number of caterpillars and sawflies that feed on horticultural crops. Common caterpillar pests include bagworms, eastern tent caterpillar, fall webworm, mimosa webworm, yellownecked caterpillar, walnut caterpillar, cutworms, European corn borer, and tomato/tobacco hornworms. Sawflies that feed on plants include the European pine sawfly, brownheaded ash sawfly, rose sawfly, and scarlet oak sawfly. Sawfly larvae resemble caterpillars; however, there is a difference.

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There are two ways to distinguish between caterpillars and sawflies. First, sawfly larvae have prolegs (stubby-looking legs) on every segment of the abdomen whereas caterpillars are typically missing prolegs. In Figure 1, a caterpillar is on the top and sawfly on the bottom. Second, caterpillar larvae have hairs or crochets on their feet while sawfly larva do not have hairs or crochets on their feet, which is shown in Figure 2, with the caterpillar prolegs on the top and sawfly prolegs on the bottom. Why is it important to know the difference between caterpillars and sawflies? Well, one of the common insecticides recommended for use against young caterpillars is Bacillus thuringiensis subsp. kurstaki that is sold under many trade names including Dipel and Thuricide. This is a bacterium that must be ingested or consumed by the target insect pest, in this case, caterpillars, in order for death to occur. However, the insecticide has no direct effect on sawfly larvae. Therefore, it is important to correctly identify the “caterpillar-like” insect before selecting an insecticide. Specimens may be sent to Kansas State University, Department of Entomology (Manhattan, KS) or the Kansas State University Diagnostic Clinic in the Department of Plant Pathology (Manhattan, KS).

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The Kentucky Derby = Finish Line Winner: ??? Kansas Insect Newsletter???

Posted on by Sharon Schroll

—Dr. Robert Bauernfeind

Yes —- there is a connection (although admittedly I may streeeetch the rubber band thin). The Kentucky Derby is held the first Saturday of May (tomorrow – May 2) and the winning horse will cross the finish line making some bettors and owners HAPPY!!! Coinciding with this Annual Run-for the-Roses are Eastern tent caterpillars and European pine sawflies which also are fast approaching the finish line for their yearly foraging activities.

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ETCs are nearly mature. I expect that by next week, they will have begun transitioning into their pupal stage. This begins with caterpillars creating their silken cocoons which are coated with a whitish/yellowish powdery substance (which can be irritating to a person’s skin and eyes).

Caterpillars may remain on the host plant, their cocoons being exposed (A) or somewhat concealed/wrapped in a leaf (B). Sometimes caterpillars may go “walkabout”, leaving their tree host to make an individual cocoon, or sometimes gathering and making cocoon clusters (C). After formation of cocoons has been completed, caterpillars transition into their pupal stage (D).

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By late May/early June, moths (A) will emerge and mate. Egg masses will then be deposited on twigs (B). A hard shellac-like coating (C) protects the eggs through the summer heat and rigors of winter. Their cycle will be renewed with egg hatch and caterpillar emergence in March of 2016.

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Regarding EPS, one has but to approach a heavily infested pine to know that the larvae are nearing the end of their feeding stage. The sparse/bare branches (a result of increasingly large larvae satisfying their ravenous appetites) signal an approaching end to their feeding cycle.

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Within a week, larvae will begin forming their thin-walled papery and somewhat leathery cocoons. Like eastern tent caterpillars, some larvae will form cocoons while remaining on their host (A). However, most will leave their host to form cocoons elsewhere. Cocoons may not be obvious because they will be camouflaged with particles of dirt and debris. When cocoons are formed under their host tree, the dirt/debris consists mostly of fecal pellets (B) which dropped to the ground by larvae as they fed.

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Unlike the rather immediate appearance of adults/mating/egg production of eastern tent caterpillars, European pine sawfly larvae aestivate (period of “rest”/decreased metabolic activity in response to higher temperatures) during the summer months. Actual pupation occurs in the fall followed by the emergence of adult sawflies (A) at which time mating occurs and overwintering eggs are inserted into needles (B). Their cycle will be renewed with egg hatch and larval emergence in late March/early April of 2016.

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Honey Bees and Bumble Bees: What Is The Difference?

Posted on by Sharon Schroll

—by Dr. Raymond Cloyd

Honey bees and bumble bees are important pollinators of many horticultural crops including vegetables, and ornamental plants in gardens and landscapes. As the weather warms, both pollinators will become more active visiting the flowers of plants in bloom. However, how different are honey bees and bumble bees?

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There are a number of behavioral differences associated with honey bees and bumble bees that are presented below:

  1. Bumble bees are more active at lower temperatures (40°F) whereas honey bees are primarily active when temperatures are around 60°F or higher.
  2. Bumble bees are active on cloudy and rainy days. Honey bees are less active at low light intensities.
  3. Bumble bees “buzz pollinate” flowers so only a single bumble bee is required for pollination whereas up to 7 honey bees may be needed to pollinate a flower.
  4. Bumble bees forage for pollen instead of nectar. They are also more efficient pollinators than honey bees because they visit more flowers in a designated time period (e.g., minute).
  5. Bumble bees are present longer during the day (early morning and late evening) than honey bees, which means they may be more susceptible to exposure from pesticide applications.

It is important to protect honey bees and bumble bees from exposure to pesticides including insecticides and fungicides. So, when using pesticides be sure to adhere to the following:

  1. Use pesticides according to the label (ALWAYS READ THE LABEL DIRECTIONS CAREFULLY).
  2. Apply pesticides when both honey bees and bumble bees are less active (early morning and later evening).
  3. Apply more selective pesticides such as Bacillus thuringiensis subsp. kurstaki (sold as Dipel), which is only active on caterpillars.
  4. “Bee-Careful” when applying any pesticides. For example, avoid directly applying pesticides to open flowers that may be visited by honey bees or bumble bees.

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