Attractants for House Flies Christopher J. Geden USDA, ARS, CMAVE

Howard (1911) described a prototype baited trap developed by C F. Hodge Methods: ”…baited with fish heads, meat scraps, watermelon rinds, and green corncobs, over which the melted waste from the ice cream freezer was poured” Results: “on one occasion he caught 2,500 flies in fifty-five minutes”

In 1945, Harvey Scudder was assigned by the US Public Health Service to assess of the efficacy of DDT. No standard methods had been developed for measuring fly populations at the time. His solution: count flies resting on a known surface area, making 3-5 counts in areas appearing to have the highest population. (Scudder, H. I A new technique for sampling the density of housefly populations)

“In constructing a neutral resting surface, consideration has been given to the fact that houseflies are commonly observed to select edges as resting places” Scudder 1947.

The Scudder grid (or grill) became the standard method for monitoring house fly populations for many years, and is still the method of choice for some organizations. World Health Organization U.S. Armed Forces Pest Management Board California Integrated Waste Management Board Advantages: Simple Inexpensive Fast Allows sampling of many sites If used consistently, can be used to measure population changes over time

Action thresholds proposed by Scudder (1998) _______________________________ Location No. flies/grill _______________________________ Restaurant kitchen 2 Residential back yard2-3 City block 5 Milking parlor15 General farm20 _______________________________ Scudder, H. I Use of the fly grill for assessment of house fly populations: An example of sampling techniques that create rough fuzzy sets. J. Vector Ecol. 21:

Axtell (1970) introduced the spot card and recommended its use as a fly monitoring tool. Advantages: Easy Inexpensive Allows consistent sampling of the same locations over time Measures activity over a week rather than giving snapshot of instantaneous fly activity Good tool for monitoring fly populations indoors Disadvantages: does not distinguish among fly species; temperature dependent

Research on fly attractants led to improvements over food-baited “Big Stinky” types of traps. Mulla (1970’s) identified triemethylamine and indole/skatole as potent feeding attractants. Carlson (1970’s) discovered the pheromone (Z)-9-tricosene Scatter baits including some or all of these components plus fast-acting toxicants were a major improvement over earlier insecticidal baits.

The challenge: attractant must compete with natural odors

Olson sticky cylinder trap with white sleeve

Farnam Fly Terminator Victor Fly Magnet

Sheltered QuikStrike with collecting pan

Comparison of Olson sticky trap, Farnam jug trap, Victor jug trap, and sheltered QuikStrike bait strip stations. __________________________________________________ Day Olson Farnam Victor QuikStrike __________________________________________________ Mean no. house flies/trap 1661 b5,462 a 2,920 a6,015 a 2679 c4,356 b 2,934 bc8,814 a 3678 c 3,080 b2,520 bc7,366 a 4515 b904 b1,611 b5,659 a __________________________________________________ Means within rows followed by the same letter are not significantly at P=0.05 (Tukey’s range test)

Comparison of Olson sticky trap, Farnam jug trap, Victor jug trap, and sheltered QuikStrike bait strip stations. __________________________________________________ Day Olson Farnam Victor QuikStrike __________________________________________________ % Females c 72.1 a 59.1 ab 47.5 b c 73.8 a 78.0 a 35.2 b c 62.2 ab 68.2 a 46.2 b d 66.5 b 76.8 a 41.0 c __________________________________________________ Means within rows followed by the same letter are not significantly at P=0.05 (Tukey’s range test)

Jug traps and QuikStrike vs sticky traps. RESULTS: Sheltered QuikStrike bait stations collected more flies than the other methods. Jug traps collected higher proportions of female flies flies (66-78%) than QuikStrike stations (35-48%) or sticky traps (16-22%). Jug trap counts on day 4 were much lower than on day 1. All of the methods except the QuikStrike stations were limited by trap saturation effects.

Effect of “fly conditioning” on attractiveness of Farnam attractant. ________________________________________________ Day No. flies collected : % Females Fresh Fly-conditioned Fresh Fly-conditioned ________________________________________________ 17,953 a8,149 a 90.9a33.0 b 2 6,762 a3,337 ab 75.9 a60.2 b 34,749 a2,429 ab 78.5 a57.0 b a 706 a 64.7 a66.8 a ________________________________________________ Means within rows under subheading followed by the same letter are not significantly at P=0.05 (Tukey’s range test)

Do jug trap collections increase when attractant is “fly-conditioned”? RESULTS: No. Fly-conditioned attractant collected about the same number of total flies as fresh attractant, but proportionally more females were collected with fresh attractant.

Comparison of traps baited with Farnam attractant, Victor attractant, or a combination. ________________________________________________ Day Farnam Victor Farnam + Victor ________________________________________________ Mean (SE) no. flies collected 1469 b1,279 ab2,295 a 22,631 b2,114 b6,847 a 32,457 b2,030 b6,812 a 41,037 b1,059 b3,662 a ________________________________________________ Means within rows followed by the same letter are not significantly at P=0.05 (Tukey’s range test)

Are the Farnam and Victor attractants synergistic? RESULTS: Yes. Attractant combinations collected significantly more flies than either attractant alone and more than expected based on the sum of the collections in the two single-attractant treatments.

Comparison of molasses (25% diluted blackstrap), standard Farnam Terminator attractant, & molasses plus Farnam attractant. ________________________________________________ Day Molasses Farnam Molasses + Farnam ________________________________________________ Mean no. house flies/trap 1 6,251 a9,835 a 8,588 a 2 4,407 a6,946 a 7,021 a 316,417 a 19,378 a 16,053 a 4 8,895 a 13,778 a 10,347 a ________________________________________________ Means within rows followed by the same letter are not significantly at P=0.05 (Tukey’s range test)

Molasses as a fly attractant. RESULTS: Molasses traps collected as many flies as traps with Farnam attractant or molasses- attractant mixtures.

Farnam attractant: The two main components are metabolic products of protein degradation that provide flies with token stimuli for the presence of protein. The attractant has a very objectionable odor and can not be used near people or food. Molasses is a complex material that may contain sugar breakdown products to provide flies with token stimuli for the presence of sugars. Quinn, B. et al Analysis of extracted and volatile components in blackstrap molasses feed as candidate house fly attractants. J. Chromatography, Series A. (in press).

From this information, we developed several candidate blends of components. A 7- component blend looks particularly promising…

Fly response to blend in assay chambers

View collections after 5-min assay period

How well will the blend compete with other natural food odors?

Can the lure be incorporated into an attract-and-kill system?