ioo ANNALS OF SCOTTISH NATURAL HISTORY 



must be regarded as alpine insects which do not descend the hills. 

 Allantus arcuatus, Forst, the common lowland species, does not 

 ascend them. The larger parasitic Hymenoptera, chiefly in summer 

 and autumn, may be watched inadvertently in their short, weak 

 flight to ascend the hills, when upward currents of warm air or 

 gentle winds help them. Ants do not appear on the highest hill 

 slopes. 



Lepidoptera. -Among the long-tongued Lepidoptera are one or 

 two true alpines, notably Erebia epiphron, Kn., which never descends. 

 Psodos trepidaria, Tr., is found at all levels. Celcena Haworthii, 

 which properly belongs to the strath, was once collected at 1800 

 feet. With this exception, the long-tongued Lepidoptera of the 

 strath do not ascend the hills. Of mid-tongued Lepidoptera, 

 Pyrausta alpinalis, Schiff., is an alpine and the common visitor of 

 the alpine plant Silene acaiilis. Other species are mostly lowland 

 and do not ascend ; but we collected on a flower of Alchemilla 

 alpina, on June 19, 1895, at 2400 feet, a single specimen of 

 Plutella cruciferarum, L., which could have had its birth only in 

 the strath. Erioccphala calthella belongs to the lower hill-sides 

 chiefly, and does not fly more than a few yards. 



Diptera. Of Syrphidae, the only specimens to be seen above 

 the strath are waifs and strays of weaker flight, and chiefly such 

 as Syrphus vitripennis, Mg., a rather flimsy insect, and Platychirus 

 albimanus, Fr. Empis contains some alpine species which, chiefly 

 in early summer, seem to do yeoman service to alpine plants. Such 

 species are Einpis lucida, Ztt., and Etnpis vcrnatis, Mg. Empis 

 tessellata very rarely ascends, and PacJiymeria palparis never does 

 so. Among the short-tongued Empidos species of Tachydromia, of 

 Hilctra, of Clinocera, and sometimes of Rhamphomyia, are found 

 high up, in summer chiefly. Muscidaa chiefly keep to low levels, 

 and the shepherds know well that sheep do not get " struck " 

 when grazing high. However, we found Lurilia and Calliphom to 

 range from the strath to the crag belt at 2000-2500 feet. Tachinidae 

 chiefly keep low. Of Sarcophagidae, Cynomyia sometimes goes high. 

 Among the Anthomyidae is one alpine species, Limnophora solitaria, 

 Ztt., but most of the order belong to the strath, although apt to 

 ascend. 



Coleoptera and other Insects. Coleoptera include the alpine 

 Anthophagus alpim/s, Payk. MeligetJies and other genera rarely 

 ascend. Of miscellaneous insects the commonest Thrips occurs 

 at all levels. 



The net result finds expression in the following table, wherein 

 we see (i) Bombi working, as it were, in two camps through spring 

 and summer one camp or centre being in the strath and one 

 about the crags ; (2) parasitic Hymenoptera ascending much in 

 autumn ; (3) ants at all levels in summer (what happens to them 



