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INSECT 'FLATS'

Nesting methods

Flats insects - Hymenoptera

Flats insects - other

Live identification

 

help to identify insects at the logs

Why identification?
Many of the insects found at the logs live fascinating lives and are amazing to examine in close-up. It is only too easy to be intrigued, but the time soon comes when you start to recognise some regular visitors and want to know more about them; familiarity requires at least a  degree of identification. The digital camera has given freedom to capture many views of the insects, from varying angles. Drilled logs set out on a south-facing wall have been proven to draw in numbers of species of hymenoptera in particular. Another wonderful tool has been the availability of low-priced binoculars developed for studying butterflies in close-up. All this adds up to a simple need to build up knowledge so as to enjoy the experience more.

The purpose of this section is to provide a reliable preliminary identification of the insects as they fly round the logs and bamboos at the 'flats'. While some will remain mysteries unless specimens are taken, I have reached the stage in life where I do not want to do this. Many are quite safe to identify as they appear in the wild, while increasing familiarity will add to the range of those recognised. By careful examination of the many photographs taken during each season, combined with features from reliable keys, there are small groups that respond to this treatment. To recognise some, where only a limited number of species are likely to be present, is much easier than toiling through a long key, depending on microscopic features. Osmia and Megachile fit this pattern and should enable people to get to grips with their identification at log trap-nests. Other groups of insects may be added as a pattern is discerned and useful features noted.

nb. Colours and appearance based on LIVE INSECTS, not dead specimens

 

Glossary
- Basitarsus            top segment of the tarsus, at bottom of leg
- Gaster                 hymenopteran abdomen
- jizz                      general recognition of insect by its actions
- Pubescence          soft, hairy surface
– Scopal brush        pollen basket beneath the gaster
- Sternite               segments seen under the gaster
- Tergite                 segments visible above gaster
- Thorax                 major body section between head and gaster



Osmia, VISUAL IDENTIFICATION OF BRITISH MASON BEES

Species nesting in wood: Osmia bicornis, caerulescens, leaiana


Females (with bushy pollen baskets beneath the abdomen, often seen smothered in pollen)


1. Scopal hairs GOLD or BRIGHT ORANGE                                                                                                                                                                                                                       2.


- Scopal hairs BLACK                                                                                                                                                                                                                                                           3.


2. Dark head and top of thorax metallic bronze-green; HORNS at side of clypeus (see line on picture); RED-GOLD hairs covering top of abdomen; hairs on lower legs bushy RED-GOLD; face with dark to black hairs; slightly dusky wings; 9-14mm.             

                                                                                                                                 bicornis


 

- Head and top of thorax black; eyes GREEN: face without horns; gastral tergites golden; tergites 2-5 appearing HAIRLESS, the sides fringed with yellow hairs; hairs on lower legs pale, with some gold; wings definitely SMOKEY; 9-12mm.        

                                                                                                                                 leaiana


 3. Top of thorax polished and lacking microsculpture; body integument black, tinted metallic BLUE and covered with greyish hairs; face without horns; dark eyes; only slightly dusky wings; hair bands at the edges of the abdominal segments; GREY leg hairs; scopa BLACK; 7-11mm.

                                                                                                                             caerulescens


 Males (no pollen basket, unobtrusive hairs beneath abdomen; constantly visiting nest holes in flight, without resting)

1. EXTRA-LONG antennae; dark head and dark bronzed thorax; face hairs distinctive WHITE; upper part of abdominal tergites 1-3 densely clothed with long ORANGE hairs; 7-13mm.

                                                                                                                             bicornis


 

- More 'normal'-sized antennae.                                                                                    2.                                                                                                                                                                           


2. Head & thorax BLACK, with blue lights; PALE face hairs; head & thorax with reddish hairs which quickly wear to show much black skin; dark eyes; distinct GREY bands at the edges of tergites, but these wear down to show dark, bare appearance; pale neutral to almost white leg hairs; 7-10mm.                                       

caerulescens


- GOLD-BRONZE head and thorax; PALE face hairs; GREEN eyes; short brown leg hairs; tarsi with short red-gold hairs; 9-10mm.

leaiana


 Although photographs are shown after each description, it is useful to put a smaller copy of each together, so as to make comparisons between sexes and other species more obvious.


 

Megachile: VISUAL IDENTIFICATION of BRITISH LEAFCUTTER BEES
Species nesting in wood Megachile centuncularis, ligneseca, versicolor, willughbiella


Male bees are difficult to differentiate, but the generally easier identification of the females should provide a guide as to what is currently flying. However, age may fade the hair colour, particularly on the top of the insect, such as to appear almost white. Visual identification is a question of detective work on numbers, rather than concentration on one insect. With experience comes a sense of ‘jizz’. This is just an aid to becoming more familiar with the insects visiting log-nests. Species are not easy to differentiate, though continued observation over a period will bring differences to light.


 FEMALES - short antennae, dense scopal brush

 

1.    From the side, long black hairs emerging from matted hairs on last visible gastral tergite        

                                                                                                                            2.                                                                            
-    Minute black matted hairs only on gastral tergite 6                                       3.

(this start-pair is conventional, but daunting, unlikely to be observed in the field. For all practical purposes go directly to the pictures and main descriptions)


 2.    ALL golden to red-haired pollen basket (seeming all one colour, though the final two sternites are actually white haired); dark eyes; Hairs on head, thorax, and gastral tergites 1 to 2, WHITE. Tergite 5 with a conspicuous fringe of white or yellow pubescence. 9-12mm

                                                                                            centuncularis


                            

   Middle of gastral sternites 1-4, scopal hairs golden, not obvious from above; the brush on sternites 5 & 6 black. Plentiful golden-brown hairs on black head, sides and back of black thorax: dark eyes; tergite 2 without bands, tergite 3-5 with, pale bands interrupted in middle, widely so on tergite 5, easily abraded with age, leaving wide, complete bands of sparse, ginger hairs. Front legs and basitarsus obviously but more or less hairy. This bee varies greatly in colour with age but one real characteristic is that the last visible segment of the gaster is TRIANGULAR, both above and from the side. 12-15mm    

willughbiella                  


3.    Scopal hairs on sternites 2-4 rich, deep, GOLDEN-RED; hairs on 5, and base of 6, BLACK; eyes dark, gastral tergites 3-5 fringed with faint bands of white pubescence, widely interrupted in the middle. Back margin of last visible tergite evenly rounded. 10-13mm

                                                                                                versicolor


-    Scopal hairs on gastral sternites 2-4 golden, 5 and 6 black. Skimpy, barely obvious, pale bands on dark gaster, widely interrupted in centre; dark eyes;  large, bulky bee; margin of gastral tergite 6 broadly rounded, almost cut off in the middle, giving a RECTANGULAR appearance to a long gaster. 15-18mm

                                                                                                ligniseca


 MALES  - long antennae, without pollen basket


1.    Pale front basitarsus, EXPANDED & flattened. 10-12mm

                 willughbiella


- Front basitarsus cylindrical and black - normal                                                             2.


2. Dark head with pale hairs; dark eyes; white hairs on side of thorax and edging the front of the abdomen (when fresh, these are gingery but quickly settle to much paler). Greyish, sparse brush beneath gaster; pale sparse, long-haired bands on top. Gaster more rounded than female, but substantial, with same RECTANGULAR appearance. Large. 12-15mm

          ligniseca



-   Pale hairs on head and edges of the thorax. The last two segments of gaster with white bands; the 3rd segment with widely interrupted band. 10-12mm

                                                                                versicolor


- Hairs on head and edges of thorax, golden-white; Gastral tergite 2 with long erect or sub-erect pale golden or whitish hairs in the middle. Pale, unobtrusive, sparse bands on gaster. 9-12mm

                                centuncularis

_______________________________________________________________________________________________________________________

As previously, it is useful to put a copy of each species photograph into a group for comparative purposes.


GENERAL ID FOR VARIOUS COMMONER GROUPS

Keys are complicated things and require hours of work on dead specimens to come up with reasonable results. Those of us looking to identify the insects visiting our logs and bamboos are only too pleased to find out what general grouping they fall into, which can prove difficult with conventional keys. The following list should enable people to come to grips with a general idea of the commoner groupings - sufficient perhaps to get a book or go online to be more certain.


Chrysidids - Brilliant red and or blue-green cuckoo, or jewel, wasps


Coelioxys - cuckoo bees with distinctive tapered and pointed abdomen



Crossocerus -small dark digger wasps, with short constricted segment between abdomen and thorax


Ectemnius - black digger wasps with yellow banded abdomens


Gasteruption - peculiar-looking small parasitic wasps with their abdomen looking as if it arises from the top of the thorax, long ovipositor in female



Hylaeus - tiny black bees looking like wasps, with white or yellow markings on their face and or other parts



Ichneumons - If an insect is seen with a long ovipositor sticking out behind, it is almost certain to be a female from this group


 Passaloecus - small dark digger wasp with a long slender segment between abdomen and thorax


Pemphredon - small densely hairy digger wasp, similar to the largely hairless Crossocerus spp., with long slender segment between gaster & thorax


Psenulus - small dark digger wasp like Crossocerus, but with stouter antennae, particularly female


Trypoxylon - dark, elongated digger wasp with the abdomen projecting well beyond the wings


Crossocerus digger wasps are the third main group, other than leafcutter and mason bees, likely to be found round the logs on any typically busy day. These small, slender black wasps fly round the holes, testing for the presence of females while later, females search for the best nest sites. There are great numbers of these around, whenever the sun comes out. This list list isof those those that might be found in this area, using logs or bamboos for nest sites. At least this cuts the list of possibles down.

C. annulipes - dark, flies from May to September

C. binotatus - black wasp with yellow banded abdomen, flies from June to September

C. capitosus - dark, flies in June

C. cetratus - dark, flies from May to August

C. dimidiatus - black wasp with yellow-banded abdomen, flies from May to August

C. distinguendus - dark, flies from June to August

C. elongatulus - dark, flies from May to September, probably the commonest 

C. megacephalus - dark, flies from May to September

C. nigritus - dark, flies from May to August

C. podagricus - dark, flies from May to August

C. styrius - dark, flies from May to September

C. tarsatus - dark, flies during mid-summer


Some identification points - possible wood-nesting digger wasps at Kyntons Mead logs


 

LIST

GASTER

ANTENNA

SCAPE

LEGS

FOVEAE (head)

Emm

Gmm

at KM

Crossocerus annulipes

black

black

E whitish front

banded

distinct

5-7

4-5.6

*

C. binotatus

black & yellow

black

yellow

Some colour

small

9-11.5

7-10

-

C. cetratus

black

Black + brown tyloidea

black

black

distinct

7-8

6.5-7.5

*

C. dimidiatus

black & yellow

Black + yellow

yellow

Some colour

small

8-11.5

7.5-9.5

-

C. elongatulus

black

black

yellow stripe

Banded joints

convex

5-6.5

5-6

*

C. megacephalus

black

black

black

black

Well developed

7-9

6-8

*

C. nigritus

black

black

black with spot

black

Well developed

6-7.5

5.5-7

*

C. styrius

black

pale

long, pale brown

black + ring

none

5.5-6.5

4.5-5.5

*

C. walkeri

black & yellow

black

Yellow + black

yellow

Yellow inner orbit

5.5-8

5-6.5

Mimumesa dahlbomi

black

black

black

black

none

7-9

6-8

*

Passaloecus gracilis

black

black

Ivory spot

banded

none

4.5-5.5

3.5-5

*

Passaloecus insignis

black

black

ivory

black

none

5-6

4.5-5.5

*

Pemphredon lugubris

black

black

black

black

none

9-12

7.5-10

*

Pemphredon wesmaeli

Black

dark

dark

black

none

8-10

7-9

-

Stigmus solski

black

pale

pale

some colour

none

3.5-5

3-4.5

*

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