REPORT OF THE SWEDISH INSTITUTE OF EXPERIMENTAL FORESTRY. 



Contributions towards the knowledge of the 



enemies of the pine and spruce amongst 



the microlepidoptera. 



by Ivar Trägärdh. 



There are amongst the moths a number of enemies to the pine and spruce 

 Avhich, as a rule, it is true, are of no great importance, but which nevertheless 

 on account of their common occurrence play a certain part. Our knowledge 

 of these in Sweden is very Hmited and in many instances insufficient, as is 

 proved by the fact that one of the species treated here, Argvresthia ilbiminn- 

 iella, which undoubtedly is generally distributed in Sweden, is now for the first 

 time reported from this country. 



Dioryctria schiizeella FucHS, a species which, according to FuCHS, has been 

 previously confounded with abietella Schiff., was found at the Experimental 

 Field near Stockholm. Full-grown larvae occurred in the middle of June, and 

 the moths appeared in the middle of July. The damage greatly resembles that 

 caused by Pandemis ribeana, but the larva does not attack the bark of the 

 young shoots, only devouring the basal part of the needles, the rest of these 

 adhering to a loose tube .spun by the larva (lig. i). For details of the larva 

 see fig. 2 and 3. 



Pandernis ribea7ia Hb. is a very polyphagous species, its larva being recor- 

 ded from Crataegtis, Rosa, Prunus, Pyrus, Rhamniis, Fraxinus, Sorbiis, Acer, 

 Tilia, Bet lila, etc. From coniferous trees, on the other hand, it seems to have 

 been recorded only once, by Wachtl in 1882, and låter authors do not give 

 these trees as food-plants. It is therefore of interest to learn that it was found 

 on spruce saplings in the neighbourhood of Stockholm. Full-grown larvae 

 occurred in the middle of June on the young shoots, which were generally 

 attacked on one side, both needles and part of the bark being eaten away 

 so that the shoots were deformed and did not develoj) normally. The larva 

 is green, lighter on the ventral side and with lighter spöts surrounding the 

 hairs, the head-capsule and the prothoracic shields being marked with dark 

 spöts (fig. 4). The antenna, labrum and mandible are delineated in fig. 5. 



Grapholiilia tedella Cl. This moth Holmgren considered one of the most 

 noxious of the enemies of the spruce. Experience gained during the subse- 

 (juent years, however, does not confirm this opinion, injury caused by this 

 moth having been recorded only once. It seems therefore probable that 

 Holmgren did not distinguish between the injury caused by this and that 

 ■caused by other moths of similar habits, but attributed them all to tedella. 

 In the vicinity of Stockholm the moth makes its appearance in the last weck 



