Sciarids
![](https://www.afbini.gov.uk/sites/afbini.gov.uk/files/styles/inline-expandable/public/images/Adult%20female%20and%20male%20sciarids.png?itok=Tjf-gENU)
Adult flies may be present on mushroom production sites throughout the year but are most numerous during May - November. On average, a mated female can lay 150-170 white, oval eggs singly, or in groups within the growing substrate. Depending on temperature, these eggs will hatch within three to four days to produce larvae.
![Sciarid larva](https://www.afbini.gov.uk/sites/afbini.gov.uk/files/styles/inline/public/images/Sciarid%20larva.png?itok=ZGncxJ8p)
It has been demonstrated that a mean of one sciarid larva in 125g of casing causes 0.5% loss in total yield. As the cost for recommended sciarid control measures also accounts for 0.5% of the value of the crop, this represents an economic threshold for this pest.
![](https://www.afbini.gov.uk/sites/afbini.gov.uk/files/styles/inline/public/images/Sciarid%20pupa.png?itok=1VnNn-fr)
Sciarid life cycle
- Adult flies may be present on mushroom production sites throughout the year but are most numerous during May – November.
- On average, a mated female can lay 150-170 white, oval eggs singly, or in groups within the growing substrate. Depending on temperature, these eggs will hatch within three to four days to produce larvae.
- The larvae feed on developing mycelium burrow into pinheads and small buttons forming a sponge-like mass.
- Mature larvae are approximately 8.0 mm in length and can remove mycelial attachments at the base of the stalk and in severe infestations may enter stalks and caps.
- Sciarid infestations in Phase I compost should be eliminated by efficient pasteurisation.
- Subsequent infestations are caused by adult females, which are attracted to the fermentation odours produced during compost cool-down.
- Environmental conditions during the spawn-running period facilitate the completion of a generation of sciarids within 2-3 weeks.