The attack on the immature mosquito has undergone an evolution since the turn of the century discovery by Walter Reed, that mosquitoes are the vectors of "Yellow Jack", or Yellow Fever. The original strategy was simple habitat elimination through the physical removal of water breeding areas. Swamps were drained, water bearing containers were dumped out, and mechanical means were employed to cover receptacles that collect and store water so as to prevent the mosquitoes from depositing their eggs, and completing their larval development.

These methods still work well for the container breeding, or swamp breeding species.

As more information about the biology and diversity of mosquitoes was collected, it was quickly realized that these control practices would not be effective across the broad spectrum of mosquito types and habitat preferences. Other control methods had to be developed which could attack mosquitoes in a variety of permanent, semi-permanent, and variable aquatic environments. The larvae of mosquitoes were found to be living in salt and freshwater marshes, flooded pastures, cedar swamps, tree holes, lake and pond perimeters, river and stream banks, roadside ditches, swales, in addition to the natural and man-made containers.

Once the aquatic connection was established, and their fresh air breathing requirements were discovered, suffocation of the larvae became the best available strategy, and the use of oils, such as Kerosene and diesel fuel, to coat the water surface, was employed. For many years before World War II, the measure of clout and success for a mosquito control superintendent, was the number and size of the fuel oil tanks under his control. Oil was sprayed liberally in every type of aquatic environment, to kill mosquito larvae and pupae, with little regard for the negative impact to non-target aquatic organisms.

The research frenzy on chemicals during World War II brought forth a new weapon for the war on mosquitoes which was simplistic and long lasting in its potency of control. The chlorinated hydrocarbon DDT was the panacea for the late 1940s and 1950s, as it could be applied as a powdered dust on the water in relatively small amounts per acre and keep killing mosquito larvae for many months, or even an entire year with a single application. It offered winter application on snow or ice as an off season manpower utilization opportunity which previously could not be done. This product enjoyed success until the development of resistance by both the mosquitoes and the public, whose sentiments were influenced by a new group of environmental crusaders who brought attention to the many negative impacts on non-target species.

Mosquito management took a major shift in emphasis from larviciding for the immature aquatic forms, to killing the flying adults with the newly developed organophosphate insecticide Malathion. This liquid chemical could easily be applied as a blanket of fog from a moving vehicle, and it would permeate and penetrate through vegetation killing the mosquito adults where they were resting.

This control method was most popular during the 1960s and 1970s and continued through the 1980s, and up to the mid-1990s with modification of the application equipment from foggers, to ultra low volume aerosol generators. These ULV applicators improved the uniformity of the insecticide droplet size, which increased dramatically the efficiency of adult control. Larviciding was still done on a limited basis, primarily with another O.P. chemical, ABATE, but the lion's share of the budget was being spent on adulticides applied by truck mounted equipment, or by fixed wing and rotary aircraft.

In 1972, Zoecon Corporation developed a new weapon for insect control which was first applied to mosquito larvae in the form of a liquid insect growth regulator (IGR) called Methoprene, with the trade name of ALTOSID Liquid Larvicide. This product is an analog of the insect's own Juvenile Hormone (JH) and is lethal to mosquito larvae such that after being exposed to Methoprene during the 4th instar, they will die while trying to pupate. The mosquito larvae live through their entire larval cycle, remaining as food for other organisms, until they pupate and attempt to become the flying vampires of their destiny. Normally, the brain of the insect stops secreting JH during the pupal stage, which is the trigger to allow the imaginal disc tissues to begin differentiation into the adult tissues. This cellular differentiation allows the development of the adult characteristics of reproductive organs, wings, specialized piercing sucking mouth parts and terrestrial legs. The presence of Methoprene in the insect's system during the 4th larval stage replaces the JH no longer being released from the brain, and prevents the triggering of adult tissue development. The larvae begin pupation, do not complete development, and die as pupae. Adult mosquitoes never emerge to become a nuisance or disease vector. The additional benefit is that there are no toxic impacts to non-target aquatic organisms.

The development of the solid formulations for ALTOSID have provided opportunities for long term mosquito larval control in their breeding aquatic habitats. Since Methoprene was highly ultraviolet light sensitive, charcoal was added as a UV light blocker to the media, plaster of Paris. This new briquette gave about thirty wet days control of mosquito development and emergence prevention. It also allowed for pre-treatment of potential breeding sites similar to the way DDT allowed early and out of season application. The XR (Extended Residual) briquette was developed next by Dr. Robert Sjogren of the Minneapolis Mosquito Control District in Minneapolis/St. Paul Minnesota, and allowed for 150 wet days of control of adult emergence. Now, applications could be done once per season, to existing, and potential aquatic breeding sites, and pre-treatment became late winter, early spring labor utilization. For many abatement areas, one XR briquette treatment per year/season was all that was necessary to sustain mosquito larval control. The XR briquettes also allowed treatment of dangerous habitats such as poisonous snake infested swamps and densely vegetated woods, during hibernation and dormancy periods before the threats were present. They are especially valuable for treatment of distant breeding habitats that require excessive travel time to manage and retreat. The addition of swimming pools to the label allowed XR briquettes to play a vital role in disaster response after major storms cut power to entire communities causing back yard pools to become instant breeding grounds when filtration shuts off. The National Guard, along with several south Florida county MADs, used helicopters to hover over and drop ALTOSID XR briquettes into swimming pools, after 135 mph winds of Hurricane Andrew cut electricity to most of southern Florida on August 23, 1992. Power was not restored for weeks which could have created a major mosquito borne disease crisis.

The ALTOSID Pellets were created in 1989 and were useful for large scale applications to habitats such as flooded pastures, rice fields, irrigated farmland, and roadside ditches. The heavy pellet is excellent for thick vegetation penetration applied by aircraft. Their small size but high temperature and pressure extruded hardness offers rugged durability lasting 6 to 8 weeks in water, and effective coverage of many discontinuous bodies of water, such as cattle hoof prints, or tire dumps. Research has shown that one pellet can give at least 30 days control of mosquito emergence in a tire. ALTOSID Pellets have been demonstrated to provide effective control of the bird to bird EEE vector, Culiseta melanura mosquitoes in white maple and cedar swamps in Massachusetts and New York. They are also perfectly designed for pre-treatment of river and stream banks in anticipation of floodwater overflows creating Aedes vexans habitats. Field use in cattail marshes and salt marshes has shown at least 60 days of mosquito emergence inhibition of Coquillitidia perturbans, and Aedes sollicitans. With the recent removal of the fish restriction from all the solid ALTOSID formulation labels, additional fish bearing water habitats such as lake and pond perimeters, can now be effectively treated with a long term residual mosquito larvicide in either the briquette or pellet form.

The liquid formulations of ALTOSID come as a 5% a.i. or a 20% a.i. known as ALTOSID Liquid Larvicide (SR-5) and ALTOSID Liquid Larvicide Concentrate (SR-20). The SR-20 was created to be used by aerial application to reduce liquid weight and volume for large acreage treatments. Microencapsulation of the liquid larvicide was required to block UV light, and this gave 7 to 10 days residual in water for both A.L.L. SR-5, and SR-20. This slow release in water over a week's time makes A.L.L. effective for single brood floodwater mosquito control where there sometimes is a staggering of the larval instar stages so that different ages share the same water site at the same time. Short term larvicides such as Bti may only control the early instars, then not be available for newly hatched or older 4th instars if development is prolonged. Since 4th instar mosquito larvae stop feeding, Bti does not affect them. ALTOSID Liquid Larvicide continues to be released into solution for an entire brood cycle, and does not require feeding to be incorporated into the body of the 4th instar mosquito larvae. This longevity of control, plus economy of aerial application has made the A.L.L. SR-20 formulation a highly effective and desirable larvicide for coastal salt marsh mosquito reduction.

Since 1994 the trend in MAD budget expenditures for mosquito adulticiding has gone from about $14 million, to about $8 million spent per year. Over the same period of time, the MAD budget expenditures for mosquito larviciding has gone from $7.5 million, to almost $15 million spent per year. Mosquito professionals have realized that it is more economical to kill mosquitoes in their own aquatic home, which can be located, mapped, monitored, and treated for a high percentage of elimination with larvicides. If they