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These insects prey 3 5 6 on Toadflax 1. Brachypterolus pulicarius 2. Calophasia lunula 3. Eteobalea serratella 4. Gymnetron antirrhini 5. Gymnetron linariae 6. Mecinus janthinus Some are beneficial . . . biological noxious weed control can be elusive and long term

The flower-feeding beetle Brachypterolus Seed capsule and root-galling weevils density and cases of multiple pulicarius was brought to North America by Gymnetron antirrhini and G. linariae were attacks. Effects of the weevil accident in 1919, probably in a shipment of released in Montana from Eurasia in 1996. on the plant reportedly are toadflax. The beetle adult eats the tips of The Dalmatian toadflax-adapted strain of G. enhanced under drought stress. toadflax shoots, and the larvae feed on antirrhini was first released in Montana in A small release of the Dalmatian pollen, flower parts, and seeds. Feeding on 1996. The yellow toadflax strain is estab- toadflax-adapted strain of yellow toadflax can reduce the number of lished in Idaho, Montana, Oregon, Gymnetron linariae occurred seeds by 80 to 90%. Although seed reduction Washington, and Wyoming. These insects are in Wyoming in 1998. As of is huge, scientists consider this ineffective generally available where yellow toadflax 2003, this was the only because it does not reduce plant populations. infestations occur. The only definitive record definitive record of G. Two root-boring moths Eteobalea interme- of Gymnetron linariae establishment in the linariae establishment diella and E. serratella lay their eggs on United States is at a solitary Dalmatian in the United States. toadflax, and their larvae then feed on the toadflax site in Wyoming. A small release of root crown. This really damages the roots and the Dalmatian toadflax-adapted strain weakens the whole plant. As the plant dies occurred in Wyoming in 1998. off, the top of the root easily breaks off, and Mecinus janthinus, toadflax stem weevil, the plant can’t grow any more. The toadflax was first introduced into Montana in 1996 moth Calophasia lunula lays its eggs on and is established in Colorado, Idaho, toadflax. The eggs hatch within 11 days, and Montana, Washington, and Oregon. Adult Dalmatian Toadflax the little gray-black larvae start feeding on the stem weevils attack both Dalmatian and Linaria dalamatica plant’s leaves and flowers. The larvae grow yellow toadflax leaves and stems. Larvae into inch-long caterpillars with black and mine the stems. In Europe, adult feeding on bright yellow stripes running the length of the leaves and stems apparently has a limited their bodies. If enough caterpillars feed on a effect under field conditions. However, mining Statewide Noxious Weed Awareness and Education Campaign stand of toadflax, they can strip off most of of the stems by the larvae causes premature the leaves and flowers. This weakens the wilting of shoots and suppresses flower Montana State University Land Resources and Environmental Sciences plants and reduces the number of seeds formation, particularly under in cooperation with produced. conditions of high weevil United States Department of Agriculture Animal and Plant Health Inspection Service Plant Protection Quarantine This insect preys on Saltcedar Diorhabda elongata Some are beneficial . . . biological noxious weed control agents

Most weed plants are weed-size, not That kind of thirst reduces streams to a tree-size. One of the largest noxious weeds in trickle, or even drinks them dry. Saltcedar the United States is saltcedar, a shrub or tree clogs river channels and reduces the size of that can grow to be thirty feet tall. Imagine a spring floods. Floods are part of the natural weed as tall as a three-story house! ebb and flow of many rivers, and many Scientists are experimenting with an insect native plants depend on floods. Cottonwood that eats saltcedar, called the saltcedar leaf trees and willows, for example, will grow beetle Diorhabda elongata. The saltcedar leaf only where floods scour mud off the gravel beetles were brought to the United States in and cobblestones. 2001 from Asia, just like the saltcedar. An Once saltcedar takes over an area, it adult beetle lays up to 200 eggs on a keeps other plants out by oozing salt from saltcedar plant. When they hatch, the larvae its leaves. The leaves dip and fall to the eat the leaves. Together, adult beetles and ground, making the surrounding soil too larvae can strip all the leaves off a saltcedar salty for most plants. Soon, birds, animals, plant. When a swarm of beetles eats a stand and even insects are driven away to look of saltcedar bare, they’ll fly a few hundred elsewhere for food. yards to the next saltcedar dining table. Saltcedar grows along streams and rivers, around springs, and along the shores of lakes and reservoirs. A stand of saltcedar can suck Saltcedar the ground dry, using 200 or more gallons of Tamarix ramosissima water every day. That’s enough in a growing season to create a swimming pool the size of Statewide Noxious Weed Awareness a city block and 9 feet deep! and Education Campaign

Montana State University Land Resources and Environmental Sciences in cooperation with United States Department of Agriculture Animal and Plant Health Inspection Service Plant Protection Quarantine 1 2

These insects prey on 4 3 Purple Loosestrife 1. Galerucella calmariensis 2. Galerucella pusilla 3. Nanophyes marmoratus 4. Hylobius transversovittatus Some are beneficial . . . biological noxious weed control agents are host specific

Researchers study insects that feed on Why is it not bad when these insects also feeds on two native particular plants. Plants that insects feed on damage purple loosestrife? plants, Swamp loosestrife exclusively are called the insect’s “host” plant. Decodon verticillatus and Purple loosestrife, once established, For example, purple loosestrife is a host plant Winged loosestrife Lythrum changes how riparian systems function. These for loosestrife beetles. The black-margined alatum, and two introduced insects were introduced to control purple and golden purple loosestrife beetles, plants, Lesser loosestrife loosestrife spread. Researchers introduced Galerucella calmariensis and G. pusilla were Lythrum hyssopifolia and these insects because they attack purple introduced into the United States from the tree Crape Myrtle loosestrife without significant impacts on other northern Germany in 1992. More golden Lagerstroemia indica. plants or endangered species. A lot of testing beetles were released than its look-alike and The black-margined and research goes into selecting biological highly mobile black-margined beetle. The beetle was permitted control agents. A technical advisory group adult black-margined beetle feeds on because it does not (TAG) helps with communications between loosestrife leaves and buds while the golden reproduce on these groups responsible for environnmental and beetle skeletonizes and defoliates loosestrife host plants. potential risk to endangered species. so severely that the plant turns brown. Once the public have an opportunity to Hylobius transversovittatus root weevils comment and the responsible regulatory deplete loosestrife root storage reserves agencies have together found no significant during the growing season and and impact on anything besides the target plant, Nanophyes mamoratus seed weevils tolerate in this case purple loosestrife, a permit is a wide range of climates and landscapes issued and insects can be placed in quaran- Purple Loosestrife where they easily find purple loosestrife. Lythrum salicaria tine. Quarantine laboratories confirm insect Depleted root storage reserves limit looses- identity, get rid of parasites, and check for trife’s ability to recuperate after the beetles and eliminate diseases before insects insects Statewide Noxious Weed Awareness defoliate the leaves. Although more damage are released into the field. and Education Campaign is done by the other insects, scientists believe Although purple loosestrife is the Montana State University the seed weevil may play an important role Land Resources and Environmental Sciences after loosestrife abundance declines and other targeted plant, the black- in cooperation with insects become less effective. margined loosestrife beetle United States Department of Agriculture Animal and Plant Health Inspection Service Plant Protection Quarantine This pathogen feeds on Yellow Starthistle Puccinia jaceae Some are beneficial . . . biological noxious weed control insects and pathogens

Some biological control agents are not While scientists learn more about fungus, insects, they are plant pathogens. Pathogens weevils with well-developed snouts and such as bacteria, fungus, and virus cause chewing parts at its tip chew deep into diseases. You have probably heard of yellow starthistle. whirling disease detected in fish when they Yellow starthistle bud weevil Bangasternus swim in a circular fashion. Whirling disease orientalis and hairy weevil Eustenopus villosus in fish is caused by a virus pathogen that were introduced from northern Greece. affects the nervous system. Puccinia jaceae is Yellow starthistle reproduces by seeds. The a yellow starthistle rust fungus that scientists bud weevil and hairy weevil are most are studying to see if it causes damage to effective in the larval stage where they cause yellow starthistle. The rust fungus is found in damage to yellow starthistle seed heads. Both southern Eurasia and the Mediterranean weevils are established in California, Idaho, basin while its original source is Turkey. Oregon, and Washington. The rust has five spore stages that are all When biological control agents are completed on a single host plant. With ideal introduced to damage a specific host plant, weather conditions spores can germinate, they rarely destroy the entire plant population. spread by wind, and infect new plants. You Once plant populations reduce in size, insects may recognize a mass of spores on an and pathogens must find host plants in other infected leaf where it will be dark to reddish- locations. Biological control is not promoted brown and powdery in appearance. The for yellow starthistle in Montana where early Yellow Starthistle fungus attacks yellow starthistle foliage and detection and rapid response to eradicate Centaurea solstitialis green stems and scientists expect it to reduce small patches is the strategy. plant vigor. The fungus was first introduced in California and recovered from its first Statewide Noxious Weed Awareness and Education Campaign generation. Scientists redistribute the fungus by vacuuming spores from infected leaves, Montana State University Land Resources and Environmental Sciences suspending in water with a wetting agent, in cooperation with and then spraying on foliage prior to an United States Department of Agriculture extended dew period. Animal and Plant Health Inspection Service Plant Protection Quarantine 2 4 3

These insects prey on 5 1 Spotted Knapweed 1. Agapeta zoegana 2. Cyphocleonus achates 3. Urophora affinis 4. Spenoptera jugoslavica 5. Larinus minutus Some are beneficial . . . biological noxious weed control moths, beetles, and flies

The sulfur knapweed moth Agapeta The lesser knapweed flower weevil Larinus zoegana is also known as the yellow-winged minutus was introduced into Montana, knapweed root moth. First introduced to Washington, and Wyoming from Greece in Montana from Europe and western Asia in 1991. The adult feeds on foliage and the 1984, it feeds on spotted knapweed roots. If larvae feed inside the seedheads. Defoliation you want to see if you have the moth in by adults can be severe in sites with high knapweed patches near you, take a black- weevil populations, Although somewhat light and suspend it over a white sheet in smaller, more reddish tibia, and covered with early evening in early August. Mostly male more grayish hairs, Larinus minutus is hard to moths will be attracted to the light. You can distinguish from L. obtusus, the blunt knap- identify them by their brilliant yellow color. weed flower weevil. The blunt knapweed Cyphocleonus achates root weevil feeds on flower weevil is larger, darker, and has dark both spotted and diffuse knapweed. The reddish-black tibia. larvae mine and gall the central vascular root The banded gall fly Urophora affinis was tissue. Adults feed on the leaves. First introduced into Montana and Oregon in introduced to Montana from Europe in 1988, 1973. It is established throughout most of the root weevil is established in California, diffuse and spotted knapweed-infested areas Colorado, Idaho, Montana, New Mexico, of the United States. It does not disperse as Oregon, Utah, Washington, and Wyoming. rapidly as the other introduced seed head Spotted Knapweed This weevil prefers hot, dry, well-drained sites gall fly U. quadrifasciata, but has been the Centaurea biebersteinii with low, scattered vegetation in temperate more persistent colonizer and is the dominant also known as areas. The bronze knapweed root borer species at most North American sites where C. maculosa Sphenoptera jugoslavica larvae attack the both flies coexist. The seedhead moth and center of the knapweed root, which becomes weevils often destroy Urophora species when Statewide Noxious Weed Awareness and Education Campaign swollen. The root borer was first introduced in they occur in the same seed head. 1980 and is established in nine northwestern Montana State University Land Resources and Environmental Sciences states. It is readily available in Oregon and in cooperation with Washington. United States Department of Agriculture Animal and Plant Health Inspection Service Plant Protection Quarantine 2 4

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These insects prey on 6 6 5 Leafy Spurge 1. Apthona flava 2. Apthona nigriscutis 3. Apthona lacertosa 4. Oberea erythrocephala 5. Spurgia esulae 6. Hyles euphoribiae Some are beneficial . . . biological noxious weed control needs many points of attack

Leafy spurge flea beetles were introduced Dakota from Italy in 1985. Sweep nets are into Montana and North Dakota from Europe not used to redistribute this small delicate between 1985 and 1993. Copper or amber fly because it will damage the very fragile Aphthona flava, black dot A. nigriscutis, and adults. Instead, clipped leafy spurge stems brown-legged A. lacertosa flea beetles are should be bunched and the bottoms wrapped established in nineteen states. Flea beetles in damp towels or damp cotton. They should feed on leafy spurge fine roots and foliage. be taken to the field as quickly as possible Red-headed leafy spurge stem borers and placed upright in a wire frame or other Oberea erythrocephala are native to Italy device so that the larvae will not be found by and Switzerland. First introduced into ants and other predatory insects. The tip (leaf Montana 1982 they are established in seven bud) gall midge adults and larvae attack the states. Their heads are red, with small black growing parts of the plant destroying the eyes and two antennae nearly as long as the shoots’ ability to flower and produce seeds. body. Some people call them the “longhorn The tips eventually die, and the plants then beetle” because of their prominent antennae. produce new shoots from below the attacked areas. These shoots are then attacked by the The adult red-headed stem borer feeds on next generation of midges. leafy spurge leaves, but not enough to really damage the plant. Instead, what kills the plant The hawk moth Hyles euphorbiae behaves much like a hummingbird and feeds on is how the female lays her eggs. She chews Leafy Spurge nectars in the flowers. all the way around the stem, sometimes twice Euphorbia esula or more, before laying eggs. The chewing “girdles” the plant, killing the shoot above. She then bores a hole into the stem above the Statewide Noxious Weed Awareness girdle and lays an egg inside. Larvae feeding and Education Campaign in the stem also help kill the plant. Montana State University Leafy spurge tip gall midge Spurgia esula Land Resources and Environmental Sciences was introduced into Montana and North in cooperation with United States Department of Agriculture Animal and Plant Health Inspection Service Plant Protection Quarantine