| Nzi trap catches - Lethbridge 1999 |
|
| Composition of the catch in an unbaited Nzi trap at the AAFC dairy (83 trap-days) and at a horse stable (13 trap-days) during late summer and autumn. Of 27,536 insects captured, 71.3% were stable flies at a ratio of 1.91 males to females. |
 |
| The
first frost occurred on 28 September, after two windy and cold days. Until
then, stable fly catches averaged 390 per day at mean daily min and max
temperatures of 8.7 and 24.9 ºC.
High catches during this warm period were associated with low wind speeds and high average daily temperature, with no statistical evidence for any change in catch through time. Catches were best explained by the following statistical model based on the logarithm of daily catch (N=31): log10 catch =
2.46 - 0.0025 wind + 0.045 temp (r2
= 0.33) After 28 September, catches were high only during warm and calm weather. The large catch on 9 October occurred after two consecutive overnight lows of -4 to -5 ºC. Stable flies were still active when trapping was terminated, after many hard frosts and a few light snowfalls. For example, on 2 November at a min/max of -4.5 and 12.9 ºC, 45 stable flies were observed on trap surfaces in the sun at noon, despite the low numbers captured for the day. |
 |
| Horn flies were captured only up until the first frost. Catches averaged 7.7 flies per day with no significant correlations with weather. |
 |
| Anthomyiidae and other small nonbiting muscids were routinely captured in modest numbers. |
 |
| Larger nonbiting flies persisted well after the first frost. The common house fly, Musca domestica, was never abundant in the Nzi catch, even though house flies were clearly present in good numbers at the dairy. |
|
|
| Fly |
N |
% |
| Stable flies | 19626 | 71.27% |
| Anthomyiidae | 3973 | 14.43% |
| Phoridae | 1406 | 5.11% |
| Nonbiting Muscids | 1006 | 3.65% |
| Horn flies | 338 | 1.23% |
| Syrphidae | 275 | 1.00% |
| Calliphoridae | 231 | 0.84% |
| Mosquitoes | 177 | 0.64% |
| Scatophagidae | 133 | 0.48% |
| Sarcophagidae | 92 | 0.33% |
| Otitidae | 67 | 0.24% |
| Hymenoptera | 58 | 0.21% |
| Dolichopodidae | 44 | 0.16% |
| Hemiptera | 26 | 0.09% |
| Nematocera | 22 | 0.08% |
| Stratiomyiidae | 15 | 0.05% |
| Tabanidae | 14 | 0.05% |
| Lepidoptera | 14 | 0.05% |
| Brachycera | 9 | 0.03% |
| Horse bot flies | 8 | 0.03% |
| Coleoptera | 2 | 0.01% |