–Dr. Jeff Whitworth and Dr. Holly Schwarting
Aphid populations remain at minimal levels in all wheat fields monitored throughout northcentral Kansas. Lady beetle and green lacewing populations are still present in these wheat fields and therefore should prevent any aphid increases.
–by Dr. Raymond Cloyd
Spirea aphid (Aphis spiraecola) is present feeding on spirea (Spiraea spp.) plants in landscapes. Spirea aphid colonies aggregate on terminal growth (Figures 1 and 2) and their feeding causes leaf curling and stunted plant growth. Spirea aphids prefer to feed on stems and leaf undersides of succulent plant growth. All mature aphids are parthenogenic (reproduce without mating) with females giving birth to live nymphs, which themselves are females. Eggs are laid on bark or on buds in the fall by wingless females after having mated with males. Eggs hatch in spring, and young nymphs develop into stem mothers that are wingless. Spirea aphid females are pear-shaped and bright yellow-green. Stem mothers reach maturity in about 20 days. Each spirea aphid female can produce up to 80 offspring or young females.
Figure 1: Spirea Aphids Feeding on Spirea Plant
Figure 2: Spirea Aphids Aggregation on Terminal Growth of Spirea Plant
Although the aphids produce honeydew (sticky, clear liquid); continual rainfall will wash the honeydew off plants. In the summer, both winged and non-winged aphids may be present. The winged forms usually appear when conditions become crowded on infested plants, in which they migrate to a more suitable food source, such as another spirea plant to start another colony. Heavy rainfall and strong winds will dislodge spirea aphid populations from plants onto the ground, where they eventually die. Frequent applications (twice per week) of forceful water sprays will quickly remove spirea aphid populations without disturbing natural enemies such as parasitoids and predators. They have a number of natural enemies including: ladybird beetles, green lacewings, and hover flies that may help to regulate spirea aphid populations.
Spirea aphids are, in general, exposed to regular applications of pesticides such as insecticidal soaps (potassium salts of fatty acids) and/or horticultural oils (petroleum, mineral, or neem-based) that may be effective in suppressing populations of spirea aphid. These pesticides have contact activity only, so thorough coverage of all plant parts is important. Furthermore, these pesticides are generally less harmful to natural enemies compared to conventional pesticides.
By — Dr. Jeff Whitworth, Dr. Holly Schwarting
Wheat fields sampled in NC Kansas over the last week have diminishing populations of aphids. Many fields had to be sampled relatively vigorously to find any aphids. However, lady beetles are still quite plentiful which should bode well for not allowing the aphid populations to rebound.
Scattered white heads are starting to be easily distinguished in the green wheat. If the stem pulls out easily, with some apparent feeding in the stem, this is from the wheat stem maggot.
The number of infested stems in always negligible relative to yield loss but often causes concern because of the easily noticed white heads.
–by Dr. Raymond Cloyd
The current wet weather and issues associated with the Zika virus have people “on edge” regarding mosquitoes (Figure 1). However, the common strategies that must be implemented to avoid mosquito bites is the same regardless of the mosquito-disease (e.g. virus) relationship. The three primary strategies that will help to avoid mosquito problems include: 1) source reduction, 2) personnel protection, and 3) insecticides.
1) Source Reduction
First of all, it is important to routinely eliminate or reduce all mosquito breeding sites, which will effectively decrease mosquito populations, by removing stagnant or standing water from any items or areas that may collect water. These include the following:
- Wheelbarrows, pet food or water dishes, saucers underneath flower pots, buckets, tires, toys, wading pools, birdbaths, ditches, and equipment. In addition, be sure that gutters drain properly and do not collect water.
2) Personnel Protection
Protect yourself from mosquito bites by delaying or avoiding being outdoors during dawn or dusk when mosquitoes are most active. Use repellents that contain the following active ingredients: DEET (Figures 2 and 3) or picaridin (Figure 4). DEET may provide up to 10 hours of protection whereas picaridin provides up to 8 hours of protection. In general, a higher percentage of active ingredient in the product results in longer residual activity or repellency. For children, do not use any more than 30% active ingredient. Furthermore, do not use any repellents on infants less than 2 months old. Clothing can be sprayed with either DEET or permethrin (pyrethroid insecticide). Afterward, always wash clothing separately. Before applying any repellent be sure to read the label carefully.
For stationary ponds there are several products that may be used, such as, “Mosquito Dunks” (Figure 5) and/or “Mosquito Bits” (Figure 6), which contain the active ingredient, Bacillus thuringiensis subsp. israelensis. The active ingredient is a bacterium that is ingested by mosquito larvae, and subsequently kills them. The bacterium only directly kills mosquito larvae and has no effect on fish or other vertebrates. Try to avoid making area-wide applications of contact insecticides because these types of applications are generally not effective, and the applications may potentially kill many beneficial insects and pollinators (e.g. bees).
What Does Not Work Against Mosquitoes
The following items will not control mosquitoes:
- Mosquito repellent plants (citronella plants), bug zappers, electronic emitters, and light traps/carbon dioxide traps.
If anyone has questions or comments regarding mosquito control please contact your state extension office or Department of Entomology at Kansas State University (Manhattan, KS).
–by Dr. Bob Bauernfeind
Pushing the envelope (as I often do), how does one use Muhammad Ali’s “Float like a butterfly, sting like a bee”, epitomized boxing style, and the movie Poltergeist tagline, “They’re here”, as an introduction to a Kansas Insect Newsletter article? I spent time on Saturday and Sunday doing yardwork. It was Sunday afternoon that (out of the corner of my eye) I frequently glimpsed monarch butterflies lazily/lightly floating by. I had noticed none the day before. So, “They’re here” refers to their arrival in Kansas (well, Manhattan) on Sunday as they were on their southward migration to their overwintering grounds in Mexico.
There are individuals with passionate interests in the status of monarch butterfly populations and activities. Avid monarch-watchers access websites which better document the current presence/movements of migrating monarchs. My sighting certainly has no official status in terms of documentation —- just a “casual” observation on my part.