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  • Writer's pictureJani Heino

A year of observing boreal insects has almost passed

Updated: Sep 26, 2023

This year has almost reached a point where insect activity is declining rapidly. Some species overwintering as adults can still be seen flying and visiting flowers, as well as some species that are active only in late autumn until the first frosts. In general, 2023 was a pretty good year for insects, despite that July was a little cooler than usual. I spotted a number of interesting insect species, with some being notably abundant in some areas. Below I have briefly described some observations I made this year.

I start this account from the spring. The first overwintering butterfly species emerged were the small tortoishell (Aglais urticae) and the comma (Polygonia c-album), both of which had emerged by late April. The comma is shown in the photo below, which was taken in Yli-Ii close to the River Iijoki. Both of these species are widespread and common in my observation area ranging about 50 km from my home to the east, southeast, north and northeast.

I made my first visit to a protected peatland area called Kärppäsuo in early June. In English, the name of this area would read ‘stoat peatland’. I did not see any stoats, though, but some interesting and typical peatland-dwelling insect species could be spotted. I was mainly looking for dragonflies in this area, but it seemed to be a little too early in the season. I only spotted three generally common species, such as four-spotted chaser (Libellula quadrimacula), shown in the photo below. Other species on wings were northern white-faced darter (Leucorrhinia rubicunda) and white-faced darter (Leucorrhinia dubia). All of these species were quite numerous in this area, but apart from some midges, insect activity in this area was not yet at a very high level.

Moving to late June and July, I visited forest roads in the delta area on the River Iijoki. Some typical butterfly and dragonfly species were exceptionally abundant in this area, including the lesser marbled fritillary (Brenthis ino). The bedstraw hawk-moth (Hyles gallii) was also active in early mornings, visiting red campion (Silene dioica) for nectar, as shown in the second photo below. I also observed a rather strange-looking, slender cerambycid beetle, Oberea oculata, in this area. This species is the third one depicted below.

Through June to August, I was also regularly observing insects in a few forest road locations. Forest roads can be important habitats for insects, especially if managed in a suitable way. I wrote a blog about this topic available here. Along the forest roads, I spotted several species, including the swallowtail (Papilio machaon), the black-veined white (Aporia crataegi), the moorland clouded yellow (Colias palaeno), the Lapland ringlet (Erebia embla), the Arran brown (Erebia ligea), the silver-washed fritillary (Argynnis paphia), the dark green fritillary (Speyeria aglaja) and the poplar admiral (Limenitis populi), as well as several fritillaries from the family Nymphalidae and blues from the family Lycaenidae. The species named are shown below in the same order as above. For the silver-washed fritillary, both a male and the silvergreyish female form were photographed within a short period during the same day.

A few species of moths flying in the daytime, too, were also seen. This one visiting thistles is Diachrysia tutti, a common noctuid moth. The second species shown below is a female of the clouded buff (Diacrisia sannio), one of the most common day-flying erebid moths in my observation area.

Later in the season in late August, I visited the same forest road areas to see if there were larvae of some moth and butterfly species along the roadside vegetation. Indeed, I spotted more than a dozen larvae of the bedstraw hawk-moth (Hyles gallii) feeding on willowherb (Chamaenerion angustifolium). Whether or not these larvae were descendants of the same female, I cannot tell, but it appeared that the size range of the larvae was too large so that all larvae would have developed from the eggs of the same female hawkmoth. Also, both the black and olive-green larval forms as shown below were equally common at this spot.

While I am writing this blog, it is already late September. By now, I have spotted various geometrid and noctuid moth species attracted to the lights of my garage. One of these species is shown below, that is, a nice-looking noctuid moth (Staurophora celsia). For photographing, I moved this individual on the birch trunk, where it seemed to easily find a good hiding place to rest for the day.

The insect season is still ongoing, so I assume I will add a few autumn-flying moth species here later. We will see which species I choose to include…


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