Asian gypsy moth (AGM) is a serious pest that can be carried on ships and cargo. AGM populations are prevalent in some seaport areas in Far East Russia, Japan, Korea, and China. If introduced, AGM would pose a significant risk to the North American plant resource base, businesses that rely on plant resources, and to market access. Vessels must arrive in North American ports with required pre-departure certification and free of AGM. It is vital that the maritime industry and the United States (U.S.) and Canadian authorities collaborate on measures to minimize the risk of AGM incursion.

Although the agricultural agencies of the United States and Canada are independent and have variances in their laws, AGM risk mitigation and exclusion efforts are a joint effort and considered a high priority.

AGM is found in Asia Pacific and there are high-density populations in ports in East Russia, Northeast China, Korea, and Japan. These infested areas are also referred to as the risk areas or the regulated areas. Countries where this pest is not native and that are currently known to regulate and inspect arriving vessels for AGM are the United States, Canada, Chile, Australia and New Zealand.

Life cycle of gypsy moths consists of four stages: eggs, larva, pupae and adult moths.

Each egg mass can contain more than 1,000 eggs. The mass is covered with buff or yellowish fuzz from the abdomen of the female. While the velvety egg masses average about 38 mm long and about 20 mm wide, they can often be smaller. Each egg has a diameter slightly greater than 1 mm.

Eggs are laid indiscriminately, usually in sheltered locations on a wide range of surfaces. I.e. on ships’ structures, containers and other cargo, which aid in the spread of AGM. Eggs are laid between July and September, depending on weather and location. The eggs remain dormant during the winter and develop and hatch into caterpillars in the following spring.

All of the damage caused by the AGM is done during the Larva (caterpillar) stage, as the insects feed on leaves during this active period of growth. AGM caterpillars stop feeding when they enter the pupae or cocoon stage.

Newly hatched larvae can survive one week without feeding. Newly hatched larvae move up host plants to newly emerging foliage and begin feeding or if this is not available, they can feed on the egg debris or be cannibalistic. The 1st and 2nd larvae instars also spin silken threads and can spread by ballooning long distances in the wind. Hence, larvae ballooning or aerial drifting may infest vessels close to the coast. Larvae mature through six instars.

The mature larvae then develops into the pupae stage in 2 to 4 days. This stage begins in June or July, depending on weather and temperature. Pupae are reddish brown in colour. After 10 to 14 days, the adult moth emerges. The adult male moths have greyish-brown wings and a wingspan of about 38 mm and adult female moths are white and larger, with wingspans up to 50 mm or more

AGM’s do not feed in the moth stage (which lasts 1 to 3 weeks) but only mate and lay eggs. The male moth dies shortly after mating and the female after laying her eggs.

Female AGMs are capable of flying up to 40 kilometres, which also increases the likelihood of their spread and distribution. Furthermore, as the female AGMs are attracted by light they may lay their egg masses on surfaces of the ship exposed to night-lights. However, if a ship is lit with shore-based floodlights, egg masses could be found in all locations.

The AGM females often lay their eggs on a vessel’s superstructure. Vessels and cargo, such as containers, are therefore known to be involved in the artificial spread of the pest by carrying the egg masses from one port to another. AGM egg masses tolerate extremes in temperature and moisture, and the larvae can, under the right conditions, hatch from an egg masse up to a year after it was attached to a vessel’s structure. After hatching, the larvae travel great distances with the wind to find food and may colonise in a new country if left unaddressed. It is therefore vital that the maritime industry and relevant port authorities collaborate on measures to minimise the risk of AGM incursions and implement procedures and policies emphasising vessel inspections.

In the larval stage of the lifecycle, gypsy moth consumes tree foliage. European race is known to favor approximately 300 plant species, while Asian race is known to consume foliate of approximately 500 plant species (Humble and Stewart). During the first three instars, gypsy moths prefer foliage of a limited selection of trees (apple, aspen, birch, larch, oak, willow, alder, hazel, etc).


Table 1. Regulated Areas and Specified Risks Period
Country Port or Prefecture Specified Period
Russian Far East Nakhodka, Ol’ga, Plastun, Pos’yet, Russkiy Island, Slavyanka, Vanino, Vladivostok, Vostochny, Zarubino,Kozmino July 1 to September 30
People’s Republic of China All ports in northern China, including all ports north of Shanghai June 1 to September 30
Republic of Korea All Ports June 1 to September 30
Japan – Northern Hokkaido, Aomori, Iwate, Miyagi, Fukushima July 1 to September 30
Japan –  Western Akita, Yamagata, Niigata, Toyama, Ishikawa June 25 to September 15
Japan – Eastern Fukui, Ibaraki, Chiba, Tokyo, Kanagawa, Shizuoka, Aichi, Mie June 20 to August 20
Japan – Southern Wakayama, Osaka, Kyoto, Hyogo, Tottori, Shimane, Okayama, Hiroshima, Yamaguchi, Kagawa, Tokushima, Ehime, Kochi, Fukuoka, Oita, Saga, Nagasaki, Miyazaki,Kumamoto, Kagoshima June 1 to August 10
Japan – Far Southern Okinawa May 25 to June 30


For vessels which have called on areas regulated for AGM during the specified periods, as

Outlined in Table 1, the following measures are required:

  1. Vessels must be inspected and must obtain pre-departure certification from a recognized certification body. A copy of the certificate, stating that the vessel is free of Asian gypsy moth life stages, must be forwarded to their U.S or Canadian agents. The inspections should be performed as close to vessel departure time from the regulated port as possible.
  1. Vessels must arrive in North American ports free from AGM. To avoid facing inspection delays, re-routing and other potential impacts associated with mitigating the risk of entry of AGM to North America, shipping lines should perform intensive vessel self-inspections to look for, remove (scrape off) and properly dispose of or destroy all egg masses and other life stages of AGM prior to entering U.S. and Canadian ports.
  1. Vessels must provide two year port of call data, at least 96 hours prior to arrival in a North American port, to the Canadian or U.S. agent. The agent is to ensure that this information is provided to U.S. and Canadian officials.

The shipping industry has significantly enhanced awareness of necessary quarantine compliance for AGM as the spread of Asian gypsy moth could have devastating effects to agribusiness and horticultural industries. This has been vital to maintaining shipping schedules. Countries are committed to working with industry partners to support measures that will reduce AGM risk at origin.

Related Sources:

Gard Alert: Asian gypsy moth season 2016
Joint AGM Industry notice 2016
Vessel’s Inspection (Photos)
Frequently asked questions (FAQ)