Diglyphus isaea
A tiny metallic green-black wasp, about 2–3 mm long, that paralyses leafminer larvae inside their mines and lays an egg beside them. The wasp larva then eats the leafminer from the outside. Females also kill young larvae by feeding on them. It is the leafminer parasitoid that US suppliers stock, used in greenhouse vegetables and ornamentals, and it builds up quickly once the weather is warm.
At a glance
- Mode
- Ectoparasitoid, plus host feeding
- Rate
- 0.25–3 /m² per release, weekly
- Ships as
- Adults in a bottle or vial
- Temp
- Active from 59 °F (15 °C)
- Humidity
- Up to 80 % RH (Arbico)
- Setting
- Greenhouses, shade houses, field
How it works
The female finds a late second or third instar larva in its mine, stings it to paralyse it, and lays one egg (occasionally more) beside it. The wasp larva feeds on the leafminer from outside and pupates between the upper and lower leaf surfaces. The pupa is green with red eyes at first, then black, and the adult cuts a round hole through the upper surface. Females also kill young larvae by feeding on them. Egg-laying estimates differ widely: Biobest gives 200–300 eggs per female, while Arbico gives up to 50 eggs but about 360 larvae killed in a lifetime.
Egg to adult takes about 16 days at 68 °F (20 °C) (Buglogical). LS Systems names the fast build-up as its main strength: it can catch a leafminer population that is rising. Biobest says it is active from 59 °F (15 °C). The best range differs by source: Koppert gives 59–77 °F (15–25 °C) and says Dacnusa sibirica may be the better choice below 68 °F (20 °C), while Arbico sells it as the warm-weather leafminer wasp, best at 77 °F and warmer. UC IPM says both are commercially available and effective in greenhouses and shade structures, as long as the houses are screened to keep the parasites in and new leafminer flies out.
Is it established?
Hold mined leaves up to the light. A working release shows as mines that stop short, with a dead larva at the end.
- WEEK 1Adults disperse from the bottle; females start stinging larvae in the mines
- WEEKS 1–2Short mines ending in dead larvae — the first sign it is working
- BY WEEK 2Wasp pupae, green at first then black, visible inside backlit mines
- AFTERRound exit holes through the upper leaf surface — the next generation is out
Release & handling
Adults arrive in a bottle or vial, usually 250 or 500, on filter paper or with no carrier. Release them the same day, in the morning or evening, low among the leaves. If you must hold them, Koppert allows one to two days at 47–50 °F (8–10 °C) with the bottle standing upright in the dark, and Arbico says use within 18 hours, at 42–50 °F.
Release the same day
Within 18 hours (Arbico), in the early morning or evening (Koppert, Arbico).
47–50 °F (8–10 °C), dark
One to two days at most, bottle upright (Koppert). Arbico gives 42–50 °F in the outer box.
Low among mined leaves
Release between the leaves (Koppert), holding the tube low in the crop so the wasps can get out (Biobest).
Close the house
UC IPM advises screening so the parasites stay in and new leafminer adults stay out.
Pesticide sensitivity
UC IPM says leafminer outbreaks commonly follow broad-spectrum, persistent insecticides applied for other pests, because they kill the leafminers' parasites. Use selective products, control ants and reduce dust around the crop. Check a product →
When to choose something else
Diglyphus is the fast, warm-weather leafminer wasp. Choose something else, or add to it, when:
- It is early spring or the house runs cool — Koppert says Dacnusa sibirica may be better below 68 °F (20 °C), and the two can be combined (Koppert, Biobest)
- The leafminer is not Liriomyza — suppliers sell it for Liriomyza species, although Arbico also lists spinach leafminer (Pegomya)
- You are growing outdoors with no screening — the parasites leave and new flies arrive; conserve wild parasitoids by avoiding broad-spectrum sprays
Where to buy
Suppliers listed alphabetically, not ranked. helpfulbugs takes no commission and does not sell insects.
- Arbico Organics250 / 500 / 1,000US
- Biobest (Diglyphus-System)250 / 500EU / UK
- Buglogical250 / 500US
- Koppert (Miglyphus)500GLOBAL
Diglyphus isaea by target
Rate and timing differ by what you are releasing it against. Each page below is the program for one pest.