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Bee swarms, some low insect populations may be drought related

COLLEGE STATION, May 8, 2013-- Drought and up-and-down temperatures are affecting insect behavior – everything from honeybee behavior to delayed emergence of pests, according to a Texas A&M AgriLife Extension Service entomologist.

“Prolonged drought and these cold snaps we’re seeing do have impacts on the food web, and that impacts bees swarming and delayed emergence of some pests such as pecan nut casebearer,” said Dr. Charles Allen, AgriLife Extension entomologist and integrated pest management coordinator, San Angelo.

Honeybee swarming is not uncommon, Allen said. Bees swarm — migrate en masse — when there’s not enough plant growth and nectar supply in an area to support a colony. Part of the hive and new queen leaves to start a new colony elsewhere, where there is hopefully a larger food supply.

However, Allen said he has received reports from other AgriLife Extension entomologists around the state that indicates swarming is more prevalent this spring. The exact cause is unknown, but it’s more likely drought-related than due to the up-and-down swings in temperature.

“This week especially, calls have been coming in to AgriLife Extension offices in the Dallas area for help coping with the sudden bee invasion,” wrote Dr. Mike Merchant, AgriLife Extension urban entomologist, Dallas, on his blog, “Insects in the City.”

“According to Shelly Spearman of the AgriLife Extension office in Rockwall County, her office is getting one to two calls a day about bees,” he said.

Merchant said spring is prime time for bee swarming, so the increase could be one of perception.

He also noted that mosquitoes are already active in many areas. In Richardson and Dallas, city and county spray trucks are already spraying due to extremely early detections of West Nile virus in the local mosquito population.

“This is very early for this disease to show up and is not a good sign, ” Merchant said. “It’s possible that we’re just looking harder for the disease after last year’s epidemic year.”

Molly Keck, AgriLife Extension integrated pest management specialist for Bexar County, noted that managed honeybee hives in the San Antonio area are “not producing as well as they did last year.”

“They really haven’t gotten into honey flow yet,” Keck said. “We’ll see what happens after these periods of rain; things may change, and swarms may start up.”

Other insect populations that may be affected by the drought or cold snaps are greenbugs, a pest that spreads disease in wheat, and pecan nut casebearers, Allen said.

With greenbugs, it’s hard to separate the direct effects of the weather from the indirect effects, he said. Greenbugs do thrive in cooler weather, he noted, while the insects that prey on them may be set back by low temperatures.

“With cooler weather, greenbugs are in the ‘winner seat,’” Allen said. “When temperatures get above 65 degrees or so, then the natural insect enemies of greenbugs get the upper hand. But with the up-and-down temperatures, it hasn’t been cold enough, long enough, to really set back the natural enemies.”

Allen said pecan nut casebearer emergence has been slow this year, and also may be due to an indirect effect of the weather. Moths typically deposit eggs on pecan nutlets soon after pollination.

“In some regions, the frost has killed the buds on trees, and the insects — at least in that case — are responding to up-and-down weather by delaying their emergence.”

AgriLife Extension district reporters compiled the following summaries for the week of April 30 – May 7:

The 12 Texas A&M AgriLife Extension Service Districts

Central: The region remained dry and in dire need of rain. Grasshopper populations were predicted to be very large. Cold temperatures slowed warm-season grass growth. There was major freeze damage to the corn, sorghum and wheat crops in some counties. Oats looked decent.

Coastal Bend: From 1 inch to 4 inches of rain fell over much of the region. Cotton growth was slowed due to cooler temperatures and the drought. Corn appeared to be recovering from a late frost. Cattle producers continued to supplement their herds as pastures recovered from drought.

East: There was little to no rain, and many producers were becoming concerned as this is usually the wetter time of the year. Some counties had high winds and cooler temperatures, with many areas setting record low temperatures. The high winds were drying out soils. Lake and pond levels were stable to low. Pasture weed control and fertilization was behind schedule due to the cold weather, as some producers continued to cut and bale cool-season forages. The cold temperatures hampered vegetable and summer-grass growth. Feeder cattle were in good to excellent condition. Fly tags, sprays and pour-on products were all being used to reduce flies on livestock. Feral hogs continued to plague some areas.

Far West: A cold front brought traces of moisture to parts of the area. On May 3, most of the area recorded light freezing conditions. The area is on alert for wildfire due to dry conditions and high winds. Livestock producers continued to provide supplemental feed for cattle. Some ranchers were starting to sell cattle due to lack of grazing. Pastures continued be stressed due to the drought.

North: Soil-moisture levels were short to adequate, which was becoming a concern in some counties as strong winds were drying out topsoil. There was another record drop in temperatures. Winter grasses were starting to mature, and some hay producers were cutting ryegrass and other winter annuals for hay. Corn in many counties appeared to be in good condition, although some fields suffered slight freeze damage that was just becoming apparent. Winter wheat across the region was in good condition; most fields were headed out. Soybeans were 80 to 90 percent planted and 50 to 70 percent emerged. Sorghum was planted and in fair to good condition. Cattle were in good condition. Pond levels were dropping. Stable flies were increasing in numbers. Feral hog activity was high.

Panhandle: For a third week in a row, there was another significant, late-season freeze. Lows in the mid-20s dealt another blow to the wheat crop. Insurance adjusters remained undecided about what to do with the crop. Some adjusters were releasing the crop while others were holding back, asking the producers to let their fields head out. Many fields were severely damaged from six major freezes, and producers were trying to recoup some of their losses. Soil-moisture levels continued to be rated mostly very short to short. Corn was developing in some areas despite the low soil temperatures. Rangeland and pastures were mostly in very poor to poor condition.

Rolling Plains: Cold weather struck the region again. While some counties avoided the third late freeze, others were not as fortunate. Wheat was still being evaluated for freeze damage, and producers were making hard decisions as to what to do with the crop: terminate it with herbicide, bale it for hay or harvest it for grain. With the continued dry weather, wheat was just below average at best before the freeze damage. One AgriLife Extension county agent reported that most wheat in his area was being cut for hay, with field averages of one to 1.5 bales per acre. Other producers opted to graze out their wheat, and were hoping they would make a cotton and/or forage sorghum crop. Cotton planting has been delayed until warmer weather and more rain. Without rain, they will be forced to “water up” the crop. Pastures were in decent condition, but cool, dry weather slowed green-up and new growth. Trees lost leaves due to cold temperatures. Little to no fruit or pecans will be harvested this year in some areas. Conditions remained extremely dry. Heavy rain was needed to fill lakes and replenish the soil profile going into the summer.

South: Scattered showers passed through some areas, improving soil-moisture levels and the condition of rangeland and pastures — some significantly and others only slightly. In the northern part of the region, temperatures became a bit cooler towards the end of the week, and light rains helped green up rangeland and pastures. Soil-moisture levels were 50 percent adequate in Frio County and 80 percent adequate in Atascosa County. All other northern counties reported short soil-moisture levels. Some eastern counties received from 1.5 to 4 inches of rain. The western counties received only spotty showers. In Frio County, potatoes were in the last stage of development and about ready to be harvested. In McMullen County, rangeland and pastures remained in poor condition, leaving ranchers without grazing, and they continued to provide heavy supplemental feed. In Jim Wells County, corn, grain sorghum and cotton were all expected to be declared a total loss. Maverick County did not get any rain, and nighttime temperatures dropped into the 40s with strong northerly winds. Farmers there were getting ready to plant summer crops. Webb County rains were expected to improve rangeland and pastures a little, but more rain was greatly needed. Livestock producers there had to provide molasses tubs and range cubes for cattle. In Zavala County, crops under irrigation, such as corn and sorghum, were doing well. Watermelon development there slowed due to unseasonably cold weather over the past two weeks. Also in that area, cabbage harvesting continued, and livestock producers further trimmed herds. In Hidalgo County, the citrus and vegetable harvests continued. In Starr County, livestock producers were able to slow supplemental feeding. Cameron County reported fair to good cattle body conditions.

South Plains: Floyd, Garza and Mitchell counties were lucky to receive some rain, though accumulations were in the tenths of an inch. Other counties remained dry. Another cold front barreled through the region May 2 -3, with damaging winds of up to 60 mph, followed by yet another hard freeze of 27 degrees on the morning of May 3, breaking records in Lubbock County. With all the late freezes, most of the wheat in the district will be cut for hay rather than harvested. Producers continued to prepare for spring planting, and most are pre-watering fields. Some producers expected to begin planting cotton within the next two weeks. Though soil temperatures were low, a couple of Lubbock County producers planted early to ensure the pre-watering moisture was not lost. However, with the freezes still occurring, some were waiting for the soil temperature to become warmer and stay consistent before planting. Rangeland and pastures still needed rain. Livestock remained mostly in fair condition, but some herds were being culled due to the continuing drought. Stock-tank water levels were low.

Southeast: In many areas, cold weather set back crop development, particularly that of Bermuda grass. Most of Montgomery County received moisture during the last two weeks, which promoted good growth of winter annuals. In San Jacinto County, summer grasses began to emerge along with summer invasive forbs and weeds. Walker County had scattered showers, and Waller County weather was unseasonably cool. In Galveston County, pasture and hay meadows greened up after heavy rains. In Orange County, the warm temperatures and adequate rains supported good forage growth.

Southwest: Scattered showers were reported throughout the Hill Country. Hail was reported in Medina County, but very little damage was observed in crops. Generally, temperatures were below normal with heavy winds. The cooler temperatures affected crop and pasture growth. Stock tank water levels were low.

West Central: Unseasonably cool weather continued. Most areas remained extremely dry. A few areas reported some rain, which will allow producers to plant hay and other spring-seeded crops. Generally, however, there was very little field activity as producers waited for more moisture before beginning cotton planting. Rangeland and pastures continued to decline. Spring green-up was stalled due to temperature swings and lack of moisture. Flies and grasshoppers were expected to be a major issue this year. Livestock remained in poor to fair condition. Ranchers continued to reduce herd numbers due to lack of grazing.

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