Meet the Weevils

Meet the Weevils

"The Weevil"

They're working even when you're Not

BIOLOGY:
Female weevils chew into the side of a young (green) puncturevine bur, deposit eggs into the seed and seal it with fecal material. Females may deposit between 250 - 450 eggs. Weevils grubs develop inside the seed and pupate therein. Each seed may produce 1-3 weevils. The life cycle from egg to adult requires about 25 days. Adult weevils may feed on the plant but do not cause appreciable damage to the plant. The number of generations per year depends on the climate. Adults overwinter in plant duff.

HISTORY:
The first release of Microlarinus Lareynii for the biological control of puncturevine in the United States occurred in 1961. In the early summer months of 1961, Microlarinus lareynlii seed weevils were released in Clark County, Nevada and Stanislaus County, California. Subsequent releases were made in Arizona, California, Colorado, Utah and Washington. The weevil became established in Arizona, California and Nevada but failed in Colorado, Washington and Utah. Today, puncturevine weevils are widely established throughout the United States.

SUCCESSES:
In 1961, 250 weevils were released at sites near Amarillo and Big Spring, Texas. By 1963 the weevil was established in Big Spring but had failed in Amarillo. The weevil was again released at sites near Amarillo and Wellington, Texas. The weevil was once again unsuccessful in Amarillo but was established in Wellington. The lack of the weevils success in Amarillo was attributed to the extreme winter conditions and the inability of the weevil to adapt. By 1966, the puncturevine weevil had spread throughout West Texas and by the mid-1970's puncturevine was no longer a weed pest in West Texas.


Puncturevine Seed Weevil
Microlarinus Lareynii (Jacquilin du Val)
[Coleoptera: Curculionidae]

Puncturevine Stem Weevil
Microlarinus lypriformis (Wollaston)
[Coleoptera: Curculionidae].


IMPLEMENTATION: Both the seed weevil and the stem weevil for biological control of puncturevine are native insects of Europe, however the first releases of these species in the United States were imported from Italy. Weevil establishment is favored by warm temperature areas associated with mild winters. Sufficient puncturevine density is another factor necessary to support substantial weevil populations. The number of weevils released in an area for control of puncturevine is dependent on both these factors; the time of year and puncturevine densities. The number of weevils released is ordinarily between 250 and 1000 weevils.

HOST RANGE:
Microlarinus lareynlii feeds on puncturevine, Microlarinus Lypriformis, Jamaica feverplant, Tribulus cistoides and Kallstroemia spp.

RECOMMENDATIONS:
It is recommended that a minimum of 250 adults be released per acre on puncturevine in moderate infestations. Where major infestations are considered to be a factor, release rates of up to 500 adults per acre are considered to be appropriate.

These two weevils are shipped mixed together as adults. Each female will produce 250 - 450 eggs. The egg to Adult cycle is 18-30 Days. The stem weevil is cylindrical in shape and the seed weevil, oval, and lighter in color.

NOTE: The listed organisms above have been tested, studied, and cleared for importation and release into the US for the control of the indicated host weed by the USDA Agriculture Research and Animal/Plant Health Inspection Service. We cannot guarantee that the release of these beneficial insects will result in population establishment and the weed control desired, because of the variable Climates. Using the weevils ourselves, we have experienced a tremendous result. The buyer assumes all responsibility for the compliance with local and state regulations that may govern the release of these organisms. We welcome your questions and concerns, and ask that you contact us if you have any concerns.

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