Tips for Releasing Beneficial Insects

Approaches to making insect releases depend on the plant material, the pest, the predator and your cultural practices. Get to know the predators being released, their lifecycles, feeding, temperature and light preferences and think these things through. Another factor is how much time you have to spend!


Open shipping containers right away and look at the insects or mites as soon as possible. Some require a magnifier or microscope. Any questions call your supplier. Beneficials in the egg or pupal stages do better if kept warm for another day or so until a few are observed starting to hatch. With beneficial insects and mites shipped in the adult or larval stages, it is best to only hold the shipment between 55º F and 65º F long enough to organize your release. Try to put them to work before the next sunrise!


Release rates are suggested per area or per plant, but in reality you want to focus on pest “hot spots” –where you have observed and marked as areas where there are more of the targeted pests. For pests that are spread out or you can’t see, distribute evenly over the area to be treated. If there is a prevailing wind, release the greater number of your beneficials along the upwind borders where they will migrate with the breezes into your field.


Patience is often needed. Depending on temperatures and what beneficial you are using to control what and what other naturally occurring predators are helping the natural biological control processes. It can take from a few days to a few weeks for the desired results to become observable throughout the field.



Keep one or two cold packs (blue ice) in the freezer so if you aren’t ready to release perishable insects, for example those in the adult stage, like predatory mites or beetles, you can replace the cold packs when your insects are delivered. Use them to keep the temperature in the box at around +/-60º F.  Be sure to insulate the cold packs with newspaper wrapping and repack so insects will not be in close contact to the cold packs and get too cold.


More about releasing…

            Green Lacewing


            Lindorus, Cryptolaemus and Stethorus

            Aphidoletes and Feltiella

            Encarsia and Eretmocerus

            Predatory Mites

            Cucumeris and Hypoaspis



Releasing Green Lacewing

High populations of ants and earwigs, if present should be controlled. They interfere with the predators activity and devour the lacewing eggs (stalks have been removed) and larvae when they encounter them in their trails. Managing ant populations, keeping them as low as possible is the single most important key to successful lacewing releases.

Lacewing Eggs

When possible, hold lacewing eggs until you see the first larvae hatching, The others will follow, so be ready to release all of them by the end of that day. Hold them in a warm area (70º F – 85º F) and at least 60% humidity  Don’t incubate them to close to a heater.  It will dry them out.  A foam insulated portable icebox warmed with a warm water bottle can be adjusted to keep the temperature and humidity optimum.  Check the environment in the holding box twice a day, replacing the warm water and damp towel as needed.  Release hatching and ready to hatch eggs when you see the first ones hatching, usually in 1-3 days.  When you must hold them longer, cool the holding box to 60º F using a block of ice to keep the larger first emerged larvae from feeding on the un-emerged eggs and smaller larvae.


Eggs that come mixed with a carrier like rice hulls are easy to release in dense foliage. Turn the container over a couple of times to distribute eggs and any early hatchers in the rice hull carrier, then broadcast evenly where you have plant-feeding pests.


There are many ways to release lacewing eggs by themselves in the bulk form (without any carrier like rice hulls). Here are a few:

Small Lacewing Egg Releases:

Place or sprinkle from a small spatula or salt shaker directly onto plants (spritz plant with water to get to stick) or on the crotches or limbs of trees.



A small foam picnic cooler makes an ideal incubator with a hot water bottle wrapped in a damp cloth. Do not raise the humidity to dew point where moisture forms on the insects. With long exposure, they can suffocate from water closing their spiracles (breathing tubes).

Catsup type squeeze bottles, enlarge opening, fill with lacewing eggs in bran.


Fill an 8 ounce plastic squeeze bottle with fine bran. Six-packs are sold at restaurant supply stores or we sell them. Slice off the pointed tip on the cap making a hole about 3/16 inch diameter so the bran flows easily out the tip when you hold the bottle horizontally. Swing it back and forth. You calibrate the tip so you know how many swings it takes to empty the bottle. Refill the bottle with the bran and add up to 5,000 lacewing eggs (close to hatching). Turn it gently to disperse eggs in the bran. (Example: if it takes 50 swings to empty the bottle, then each swing is going to release approximately 100 eggs.)


Bigger Lacewing Egg Releases:

Mix lacewing eggs in water and spray onto foliage. Use right away. Don’t store in water!.A clean, non-toxic sprayer can be adapted so the nozzle does not have mesh to block the flow of eggs. Best not to set up more than one gallon, keep jiggling the tank to aerate the water and keep the eggs in suspension. Finish spraying ideally within 15 minutes and not longer than 30 minutes. Lacewing eggs, predatory mites and bulk Encarsia can also be sprayed from a dusting sprayer tank in a bran carrier with an appropriate nozzle.


Really Big Lacewing Egg Releases:

Mix lacewing eggs (and predator mites if also being released) in a bran carrier and release by remotely controlled aircraft or through a tube rigged ideally through the floor of an ultra-light aircraft. This takes planning and trials to work out the controls and flow to cover the area being treated.


Lacewing Egg Cards:

Cut cards into 30 tabs and use the door hanger style hook to hang on leaves or small branches. Hang inside the canopy on side toward the sun. The oval green eggs on the card turn silvery grey as they get ready to hatch and then they split open.


Lacewing Larvae In Paper Honeycomb:

Peel the organdy mesh back to expose several cells, turn the unit over and tap soundly over a plant. Pull back more organdy, move to another plant, and tap again. Individual larvae can be moved to plants using a fine artists paint brush (such as No. 1). The larvae will eat each other if crowded, so try to distribute them among the plants to be treated.


Lacewing Larvae In Bottles:

Sprinkle directly onto low growing plants. For taller plants with smooth leaves, sprinkle leaves with water first and the rice hull carrier will stick to the leaves long enough for the larvae to walk on to the leaves.


Lacewing Adults:

Adults fly at night, so when you tap the adults out of the shipping cylinder they will only fly a short distance and hide in the foliage in your field near where you release them. Adults left in the cylinder could be prey for ants. Egg-laying by lacewing adults is stimulated by a diet of nectar and honeydew produced by insects, such as aphids, mealy bugs, psylids, leafhoppers, whitefly, spittlebugs and scale insects. You can hold or attract populations of lacewing by applying artificial honeydew, such as is contained in ‘Insect Food’,  a product that simulates insect honeydew.



Determine any prevailing wind at night and release more on the upwind side of the nighttime prevailing winds. They can also be released into insect habitat plantings. See habitat seeds.

Ladybird Beetles (Converging Ladybug):

Release ideally at dusk or early evening after sprinkling water in the release area. Insects are thirsty after traveling. Ladybugs are flighty—they can disperse completely within 24 hours. Even when released with special care, many will fly anyway. It is in their nature to fly and seek food.  When they find a ‘hot spot’ of pests (prey), after feeding, they lay a few eggs.  They lay eggs when they feed on hot spots of their special food choice.  Howeverk, they forage constantly on all kind of insects, and nectar and pollen. Place the beetles directly on the infested plants. You can hold more in the area with Predalure insect attractant or artificial honeydews. Use our Insect Food or a mix of molasses and dry brewers yeast sprayed or distributed on ‘foodsticks’

Lindorus, Cryptolaemus and Stethorus:

These other predatory beetles are attracted to light, so the main consideration is to release if possible after sundown. A soft brush is useful to lift a few beetles out of the vial and place them near their prey.

Aphidoletes and Feltiella:

These come in the pupal stage, emerge as adult flying midges, laying eggs that become predatory larvae. You can simply remove the lid and set the trays or vials out and allow the adults to emerge in an ant-free area. However, to speed up the emergence and protect them from overhead sprinklers or predators, it is often better to hold them in a warm fairly humid place with the lid on until you see the first adults flying, then set them out. Bulk amounts of Aphidoletes should be divided up into incubation and release containers (can be something like a squat half-pint deli container or pint size cottage cheese cartons). Place ideally some medium sized vermiculite leaving at least an inch of head room and cover with a tight lid. When the first adults emerge, place the containers in the field with the lids removed.

Encarsia and Eretmocerus on cards:

Distribute cards in area to be treated, putting more in areas with more whitefly. Wasps fly from the cards to the plants so the cards don’t need to be in contact with the plants – they can be on wires, trellises or supports.


Encarsia and Eretmocerus as loose scale:

Loose bulk whitefly parasites are in the pupal stage of the whitefly scale. They are sprinkled on plants with a coarse pepper shaker.

Predatory Mites:

Release mites as soon as you can after receiving them, concentrating on hot spots. Hold most mites at 50 ºF (cold pack in a styrofoam box) for maximum one day. Do not place in a refrigerator (40 ºF) as this is too cold for many mites and will kill them. Persimilis and Longipes tend to move vertically upward, so release low on the plants. Fallacis moves laterally, and usually away from light.


For mites shipped on leaves, lay the bean leaf over a branch or tuck into foliage. You have to assess the numbers per leaf and put more where you see more pest mites and less where you see less.


Mites packed in corn grit, bran or vermiculite carrier can be divided into release stations made of post-it notes, French fry bags or sealed envelopes cut in half. Or they can be sprinkled directly onto leaves if the carrier will stick. If not, spray leaves with a little water and sprinkle grit onto wet leaves. The water will not affect the predator mites, which will walk off the carrier onto the leaves.


Between 3 and 10 French fry bags or sealed envelopes cut in half will hold 1,000 predatory mites with their carrier. Staple with a leaf inside the paper. Predator mites will promptly disperse.
Post-it notes (sticky note pads) can be wrapped around stems or branches to form a platform for releasing mites.
Syngenta’s Universal Release Box provides another beneficial release station option.



Cucumeris and Hypoaspis:

These predators are adult mites shipped in a carrier that is also a growing medium. The bulk forms are are sprinkled on the soil. The Cucumeris climb into the plant and Hypoaspis go into the soil. They can be held for 1-2 weeks at cool room temperature 60º F. Cucumeris is also available in teabag or paper bag style release stations to hang on foliage where all stages of the predators are reproducing in a time-release system.


These micro-wasps come as pupae inside of moth eggs loose or glued on cards. Cut cards into 30 tabs and distribute over area to be treated, every 4th tree works well especially if the canopies are touching. Our own Jan Dietrick invented the card production mold that provides a way to hook individual tabs on branches. No longer so abundant, small plastic film canisters with holes poked in the lids can be hung and used as permanent release stations. Place a new square of Trichogramma in each canister each week of the release program.


Spray or shake loose Trichogramma using the same tools mentioned above for lacewing eggs and Encarsia. Trichogramma can also be suspended in water and sprayed out, but keep time in water under 30 minutes. A great deal of effort and expense has gone into aerial release technology; however, at this time it is neither well-proven nor available.



Give Trichogramma wasps extra TLC by feeding them some carbohydrate when they first emerge from the moth eggs. Make ‘honey paper excelsior’ by spreading warm diluted honey on wax paper, letting it dry and shredding it. Place a drop of honey and a drop of warm water on a sheet of waxed paper, fold the paper in half and rub the two sides to mix and spread out the honey over the paper. Cut into strips and place in the incubation container with loose or carded Trichogramma. With this carbohydrate meal at emergence time they will live one to four days longer than without a source of carbohydrate.


Incubating either in paper wedge cups or small vials is some trouble, but it’s one way to get the most reliable performance for your money from Trichogramma. The paper wedge cup is a cheap and effective incubation and mating chamber. The cup hold the males until the females emerge, maximizing swarming and mating. Hold in a warm place (see about incubating lacewing eggs above). With paper wedge cups, poke 2-4 holes in the cup with a blunt needle or nail at time of release into the field – large enough for wasps to emerge but small enough to keep ants out. The mated females will be attracted to the light at the holes, escape and spread out on light breezes around the area. When incubating in vials, open them and place where Trichogramma will fly out.


Poke holes in wedge cup with dissecting probe to allow adult Trichogramma wasps to escape


A simple way to incubate and release Trichogramma is to let the females mate with the males is in a white paper sack or a wide-mouth quart or gallon jar. Place 100,000 parasitized moth eggs per container with a handful of honey paper excelsior and fold the top of the bag or seal the jar with a tight-fitting lid. This contains enough for a half an acre to two acres depending on the particular program, so assess the distribution of wasps in the container and walk the release area opening the container periodically to allow wasps to escape. If using a glass jar, wrap it with something to make it darker inside so the wasps will be attracted to the light and fly out when you open the lid.