Optimizing applications of Chrysoperla rufilabris eggs

Improving methods for Better Pest Management by providing practical and applicable information to our customers.

Beneficial Insectary's modern insect rearing methods provide healthy egg, larval, and adult stages of Chrysoperla rufilabris (green lacewing) for mass releases in biological control programs. We provide large quantities of each stage that are packaged according to your needs. Our shipping procedures ensure timely arrival of viable insects.

To advance Better Pest Management, we strive to provide applicable and practical technical information to our customers. We encourage the exchange of information to improve efficacy in the use of our products.

The purchase of Chrysoperla rufilabris eggs and the delivery of the egg stage of this effective predator is increasing rapidly. Customers report very good results with Chrysoperla egg releases on a variety of pest species, including the grape leafhopper in California, the longtailed mealybug in interiors and aphids in citrus groves.

As new release methods for Chrysoperla rufilabris are developed, we will provide assistance to our customers that will enable more knowledgeable utilization of products that achieve Better Pest Management at least cost.

The following recommendations, along with easily recognizable biological and physical clues, are designed to assist customers in the effective delivery of the most optimally developed Chrysoperla eggs to the target pest.

Beneficial Insectary rears Chrysoperla in age cohorts of 0-24 hours old. There are peaks of oviposition in Chrysoperla culture; therefore, most of the eggs are produced within a 12-15 hour period. Consequently, hatching or larval eclosion also peaks within this more narrow time frame. Chrysoperla eggs are harvested and prepared for shipment in a process that requires 36 hours. Eggs shipped to customers are therefore 36-60 hours old. Eggs, shipped overnight in cold pack containers, range from about 48-72 hours old upon arrival.

Very large orders may require that several days of egg harvest be combined. In these cases, harvested eggs are held at the insectary, under controlled cool temperatures, until sufficient quantities for shipment are processed. This careful cooling process allows for aggregated development of the combined egg harvests, thus nearly all eggs in a group shipped to a customer will hatch within 24 hours of each other. Final hatch of eggs depends upon temperature, humidity and stage of egg development at the time of receipt and/or release.

When eggs are received by the customer, the egg membrane color will be a combination of green, pale yellow and gray (Fig. 1). A few non-viable eggs will remain bright green. Careful examination of viable eggs with a 14X hand lens, a powerful magnifier, or a dissecting scope, will reveal the beginning of abdominal segmentation by the developing lacewing larvae. Abdominal segmentation appears as a series of pale white bands on a light gray to pale brown background.

As the lacewing larvae within the eggs continue to develop, the egg membrane becomes dull yellow. The developing larvae within become a darker gray, and abdominal segmentation is more readily apparent (Fig. 2). Some eggs may begin to hatch at this point.

When the membrane of about 95% of the viable eggs is dull gray, and the developing larvae are gray with distinct abdominal bands and readily visible eyespots (Fig. 3), hatching rapidly accelerates and will be nearly complete within 12-15 hours .

After the lacewing larvae emerge (Fig. 4), the empty egg membranes become ghostly white (Fig. 5). After emergence of all larvae, the debris that remains consists of a few bright green non-viable eggs, white empty eggs and, usually, some brownish fecal material.

We recommend the following four criteria as the best means to determine that Chrysoperla eggs are ready for immediate field release: 1. egg membranes are dull gray; 2. abdominal bands of larvae are distinct; 3. larval eyespots are readily visible; 4. at least 1% of the viable eggs have hatched. Refer to Figures 3, 4 and 5.

In case of inclement weather or logistic problems, egg hatch can be delayed by cool temperature incubation. To retard development, we recommend that eggs be cooled only on the day of receipt. Cooling older or well developed eggs may lower the hatch rate and decrease predation by the larvae. Eggs should not be held at temperatures below 60^oF at less than 50% RH to delay hatching.

We recommend that newly received eggs be held no more than 3 days under the recommended temperature and humidity levels.

Immediately Immediately prior to release, the eggs may be held at cooler temperatures no lower than 60^oF for very short periods during transport to the release site and during the release period.