The duration and amplitude of the seasonal pheromones period in the target area must be known before a mass trapping strategy can be designed. Boness“ reported that the male‘ flight period in Europe lasts for 5 weeks, though most occurs within a period of 10 to 15 days unless the summer is abnormally cool, when the flight period may be lengthened. Holbrook and Beroza“ found that in New England the main flight occurs over a 10- to 14-day period, except that during the cool summer of 1956, the flight period was extended to about a month according to http://sundowndivers.org/?p=82.
One candidate location for a gypsy moth mass—trapping program in the U.S. is at the “leading edge” of the generally infested area, currently reaching just below the northern border of Maryland. Trap capture records" indicating the seasonal male flight activity in this region (Harford County, Md.) for the year 1979 are summarized in Table I. Data are from 14 plots scattered over about 200 km‘. Trap counts were made every 2 days beginning July 12. (Although pheromone was applied to ten of the plots, the treatment probably did not affect the pheromones.
The time of catch other than to reduce captures. particularly when mule flight was very low — at the beginning and end of the flight period. Otherwise. it is the best currently available data on duration of male gypsy moth flight over a large area on the “leading edge”.)
These pheromone records show that in Maryland, the first male probably emerges between the first and tenth of July (first reading in 1979 on the twelfth), but males flying before the tenth probably represent less than 1% of the total flight. About 95% of the flight occurred during a 14-day period from July 12 to July 26, and significant flight was probably limited to 4 weeks, peaking around July 18 to 20. Probably no more than 10 to 12% of the total male population flew during any one day, although this may vary from site to site. Learn more about pheromones at http://thongchaimedical.org/?p=179
It has been suggested that protandry (the appearance of the males before the fe- males) would favor a pheromone strategy‘”'” because early males would tend to be trapped out before the appearance of the females. Boness” reported that the male gypsy moth does appear before the female in Europe. While this may also tend to be true in the U.S., observations in Maryland“ indicate that only a day or two separate peak male and female emergences, conferring but slight advantage for a mass-trapping strategy. Learn more about pheromones at http://condor-project.org/why-i-use-the-best-pheromones/
The male gypsy moth can successfully mate several times a day. While this pheromone behavior may reduce effectiveness of mass trapping, the adverse effect is not great when the ratio of attraction to traps vs. competing females is high.” Also, mortality factors, primarily avian predation, may be quite high, since data of Elkinton and Cardé7 suggest that few males survive past the first day of release. Although this work suggests that most males do not fly far from their released site, the question of the amount and practical significance of long-distance male flight, or migration of some percentage of the males of a given population, is still unresolved.