Whitefly are sapsuckers of plants and can consume huge amounts of sap if they are left untreated. Much of this sap contains sugar and is excreted back onto plants by the Whitefly as honeydew, which sooty moulds will grow on. Plant growth can be stunted, or slowed, when Whiteflies are present in large numbers. Leaves will also wilt or drop if the Whitefly remain present. Produce, such as Tomatoes, can be soiled and left with sticky deposits. Whitefly can also transmit plant viruses from plant to plant. The most common Whitefly species that attacks indoor grown plants is the Glasshouse Whitefly (Trialeurodes vaporariorum), which Encarsia will treat.
Encarsia formosa are natural parasites of Whitefly. The Encarsia Wasps are tiny with a yellow abdomen and black upper body. Most of the Encarsia formosa population are female and will lay their eggs inside the Whitefly larvae. The Whitefly larvae then dies and turns into a parasitised mummy. This is black in colour and will contain a developing Encarsia wasp. The wasp grows, consuming the honeydew and body fluids of the parasitised larvae, before eating its way out by puncturing a small hole through the Whitefly mummy in order to emerge. The newly emerged Encarsia will then start to search for other Whitefly larvae to lay eggs in and kill. The wasps will leave black scale on the underside of leaves which will be evidence of the parasitised Whitefly scale of successful kills.
The Encarsia wasps have a very efficient flying pattern and will search plants for Whitefly. Once they locate the Whitefly larvae, they will stay in such an area until all the larvae have been parasitised for these hosts to feed on.
This process is one of the oldest forms of biological control and has been used for many years, especially by tomato growers. It has a huge advantage over traditional chemical pesticide controls in that the Whitefly are unable to become resistant to attack by these tiny parasites.
Temperature and day length will have a big impact on the activity levels of Encarsia. The Wasps will only fly in the day and low light levels will reduce their activity.
The Encarsia formosa are only fully active at temperatures of 17℃ plus. There may be minimal activity at lower temperatures but it will be slower and the Encarsia life cycle will take longer to develop. Temperatures above 17℃ will also, however, increase the activity and effectiveness of Encarisa. Even at higher temperatures the Encarsia life cycle remains quite long, though and it may take time before you see results, so some patience is required.
The Encarsia formosa will develop more quickly than the Whitefly in optimum conditions however and will be able to easily establish control over Whitefly populations once they have become active.
The Encarsia formosa are more effective if introduced in a controlled environment such as a greenhouse or glasshouse.
Introduce Whitefly Killer before Whitefly are in high numbers for best results.
First open your package carefully inside the area in which you wish to release them. Next bend and tear off the strips of the card, opposite the mounting hole, and suspend the cards on the plants you wish to treat for Whitefly infestation. This should be approximately 75cm under the plant head.
Ensure the cards avoid direct sunlight and do not directly touch the Encarsia pupae.
All the Encarsia will have emerged after a week, and most will have done so in the first few days, so each card can be removed and replaced after a week. More cards should be hung in areas of higher Whitefly activity.
Whitefly Killer Cards are supplied as a number of cards with tiny parasitised Whitefly pupae attached within them. We offer boxes containing cardboard strips of 10, 25, 50 or 250 cards each. As an indicator of how many wasps are contained in these cards 10 cardboard strips, will hatch 3,000 parasitic wasps, and 50 cardboard strips will hatch 15,000 parasitic wasps, for example.
If temperatures or light levels are low but Whitefly are still present, use our Yellow Sticky Traps and SB Plant Invigorator sprays on a regular basis until it is warm enough to introduce Whitefly Killer. These products ensure you can still achieve control over Whitefly populations and limit damage to your plants at any time of the year.
A programme of Encarsia introductions is the best way of achieving results from Whitefly Killer Encarsia Wasps. Professional growers, for instance, have found that introducing Encarsia in glasshouses with a programme of introductions is the most effective method of controlling Whitefly infestations. A programme ensures populations of Encarsia are maintained to counter Whitefly populations when plants are vulnerable to attack, and helps ensure Encarsia are present as soon as the Whitefly appear. If there are already very high numbers of Whitefly present before Encarsia introductions have started, control of the pest can take a longer period of time. See our Encarsia formosa programmes here.
Encarsia Formosa is a living creature and can be affected by any chemical pesticides used within the previous few weeks. As a general guide, refrain from using Pyrethrum or SB Plant Invigorator 2 days prior to use. Other chemicals insecticides can have long lasting residues that could harm Encarsia Formosa and other predators for much longer periods. Refrain from using these products or check with Dragonfli for information on the effect of these products on our predators.