Canopy fogging in forest insect studies

In the majority of global forests the insect fauna is extremely poorly known and most of the species have not even been named. Only just recently it has gradually been revealed how incredibly huge diversity there exists especially in the canopies of tropical forests.

Finnish insect fauna is one of the best know in entire world. Finland is among the leading countries in terms of research on the effect of silvicultural practices on species. Therefore it is amazing that we know practically nothing about the canopy insect fauna of Finnish forests.   Canopy fogging has not been previously used as a sampling method in Finland.  In Norway, with a similar canopy fogging method and comprising only 24 trees, scientists found several new invertebrate species to country and nine totally new species to science.

Research method

Canopy fogging is based on the spraying of pyrethrine, which kills the insects very rapidly. The falling insects are collected from the ground.  The chemical used is not poisonous to other animals such as birds in the trees. The used natural pyrethrine breaks down due to UV-radiation within ten minutes and is thus safe to use. The successful application of canopy fogging requires completely windless circumstances and therefore, in practice, the spraying is carried out only in nights. Samples can be collected relatively easily with this method; otherwise sampling would be very difficult with traditional sampling methods.

The canopy fogging method has revealed huge amounts of earlier unknown invertabrate species from Europe and rain forest areas. © Petri Martikainen 


The aim of this project is to test the applicability of canopy fogging method as a sampling method of forest insects in Finland.  In addition, we will study the variation of species among trees, forest vegetation types and between pristine and managed forests.

Research group

Canopy fogging studies are carried in cooperation with the Finnish group led by Petri Martikainen from the University of Joensuu and with the joint German-French research group led by Jörg Műller from the National Park Bavarian Forest. The group has ample experience from this method in Central-Europe. The collected sample material will be identified on group level and send to corresponding group experts for a species level identification.


Sampling was carried out as planned in summer 2009, and altogether 126 trees were studied. According to first estimates more than 80 000 invertebrate specimens were collected!

A bunch of yet undetermined ichneumonid species from a Finnish tree canopy. © Petri Martikainen

Further information

Petri Martikainen, University of Eastern Finland,

Published 2013-06-20 at 12:46, updated 2013-06-20 at 12:46