Author: (Linnaeus, 1758)
Spruce cone moth
Spruce seed moth
Adult: 10-15 mm wingspan; distal three-quarters of the forewing with golden yellow irroration; median field of wing with a transverse medio-dorsal stria extending to the costa; ocellus weakly marked. Hindwing fuscous, paler basally in males.
Egg: hidden in the interior part of the cones of the host plant.
Larva: Head light or dark brown; prothoracic plate light brown, translucent, darker on postero-lateral margin; abdomen pale yellow, slightly shining, pinacula concolorous; anal plate light brown, weakly sclerotized.
Pupa: shining pale brown, slender, abdominal segments deeply incised, cremaster a short flat knob; in the larval habitation, usually spun up in a cavity in a large scale of the cone.
Cydia strobilella adult 1
Cydia strobilella adult 2
External characters: 10-15 mm wingspan. Forewing ground colour white or cream-white, overlaid with grey-brown except well-defined interspaces between blackish brown costal strigulae, the interspaces producing metallic plumbeous striae, medial area transversely bisected by a blackish brown stria; distal three-quarters of wing irrorate (tips of scales) with golden yellow, the irroration being strongest along the termen; fasciate markings blackish brown, irrorate with golden yellow; basal fascia obsolete; sub-basal fascia moderately strong, its inner edge diffuse, the outer edge well-defined, obtusely angulated at middle; median fascia outward-oblique to above middle, broadening and continuing direct to dorsum; ocellus poorly developed, edged laterally with metallic plumbeous striae and usually containing three or four indistinct black dots along its outer margin; cilia concolorous with wing at base, otherwise grey, with a black sub-basal line interrupted subapically and again before tornus and sometimes with a third interruption at tornus. Hindwing fuscous, paler basally; cilia cream-white, with a fuscous sub-basal line (Bradley et al., 1979).
male gen. Cydia strobilella
Genitalia: Base of valva barely demarcated from short broad neck. Sacculus without special angular protuberance under basal opening. Cucullus covered with bristles up to ventral angle. Cornuti sharply distinguished in size: a group of long cornuti which are two to three times longer than diameter of aedeagus and a group shorter ones (half the length).
External characters: Forewing colouration and markings as in male but hindwing uniformly fuscous.
female gen. Cydia strobilella
detail fem. gen. C. strobilella
Genitalia: Seventh sternite entire, its median field not connected with lamella postvaginalis; the latter relatively small and simple. Last segment of abdomen elongated into a very long telescopic ovipositor. Papillae analis two to three times shorter than apophyses posteriores. Ductus bursae sclerotized; inception of ductus seminalis situated near antrum; ductus seminalis not sclerotized.
Goncharenko and Emel'yanov, 1993, analyzed larvae from different populations by starch gel electrophoresis and found that gene pools from Europe and Eastern Asia were sharply separated, indicating that there are two subspecies of Cydia strobilella involved.
Cydia strobilella is an univoltine species. In years in which spruce trees fructify poorly, up to 98% of the population may remain in diapause for an additional 1 or 2 years. Their flight period occurs during the flowering of the host trees, i.e. from the middle of April until the beginning of June. The males appear 1 or 2 days before the females. Copulation takes place within a few hours of emergence. Oviposition starts on the same day. The female pushes the telescopically extended caudal end of her abdomen between the scales at any place on the flower and deposits her eggs singly, in pairs or in groups of three. The eggs are not glued to the substrate, but wedged between two scales. The scales close after pollination, thus hiding the eggs in the interior part of the cones. The adults live only a few days.
The neonate larvae mine through the scales until they reach the outer layers of the spindle, where they moult. The second instar larva bores itself into a seed, eats it empty and leaves the seed, filled with excrements, through a second hole. The moult towards the third instar follows inside another seed. Feeding is then continued inside the spindle, in which the larva moults to the last larval instar in the first half of June (in Southern Norway). Before hibernation a hole, through which the adults emerge later on, is gnawed by the full-grown larva at the base of a scale. The whitish full-grown larvae are about 10 mm in length. Up to ten larvae or even more may be found in one cone. Pupation takes place inside the spindle after termination of diapause.
Cydia strobilella undergoes diapause during the last larval instar. The proportion of the population that resumes development after one, two or three hibernations varies from year to year. The factors that influence the duration of diapause are the same that induce flowering. Synchronization of the development of host tree and of Cydia strobilella is presumably to a large extent influenced by summer temperatures.
The pupal stage lasts about 2 weeks (Bogenschütz, 1991; Postner, 1978).
Picea abies, Picea ajanensis ; occasionally also encountered on Pinus sylvestris, Pseudotsuga menziesii and Abies.
In North America, the species has been recorded from Picea engelmanni, Picea glauca, Picea mariana, Picea pungens, Picea rubens and Picea sitchensis.
larvae feeding in cone
Infested cones maintain either their normal shape, or are bent and excrete resin. Some of the cones drop prematurely. They open insufficiently, thus hampering the release of the seeds. Infestation also directly affects the yield of seeds: one larva per cone may cut down the number of seeds by half, a total loss of seeds may be expected at infestation levels of six larvae or more per cone.
Outbreaks of this species are especially common in Northern and Eastern Europe. Spruce trees that are fertilized with nitrogen and phosphorous are more suitable for the development of the larvae than trees that do not receive fertilizers (Bogenschütz, 1991).
Europe to Eastern Russia, China and Japan. The species is more abundant in the northern part of its range than in the southern part. The species also occurs in Eastern Canada and the northern part of the USA, where it has been known as Cydia youngana (Kearfott).
E 8Z 10-12Ac : 1
E 8E 10-12Ac : 1
(Witzgall et al., 1996b)
Of certain importance among the natural enemies are Ichneumonidae, Braconidae and Eulophidae. In a few cases up to 67% of the larvae were killed by these parasitoids, but on average parasitization rarely surmounts 10%.
Nemeristis transfuga and Apechthis strobilellae (both Ichneumonidae) are the main parasitoids of Cydia strobilella in Scandinavia. Nemeristis transfuga reached parasitization levels of 20% in Southern Norway, Apechthis strobilellae of 10%. Less effective parasitoids are Bracon pinett Thomson (Braconidae) and Elachertus nigritulus (Zetterstedt) (Eulophidae) (Bogenschütz, 1991).
In Latvia, promising results were shown after a one-year test to control the species with the egg parasitoid Trichogramma pallidum (Meier) (Trichogrammatidae) (Saksons and Saksons, 1973).
In North America (Colorado, USA), an unidentified species of Elfia (Tachinidae) parasitized the larvae of Cydia strobilella (Schmid et al., 1981). In Alaska, Scambus protentus Walley and Scambus longicorpus occidentalis Walley (Ichneumonidae) were identified as parasitoids (Torgersen, 1973).
Cydia conicolana (Heylaerts)
Cydia conicolana adult 1
Cydia conicolana adult 2
Cydia strobilella is occasionally encountered on Pinus. Cydia conicolana (Heylaerts) can also be found feeding in the cones of Pinus spp.; it occurs in the central belt of Southern and Western Europe, Asia Minor and South-Western Russia. Cydia strobilella can be distinguished by the golden yellow irroration on the distal three-quarters of the forewing and the brown transverse stria in the whitish field between sub-basal and media fasciae.
Also compare genitalia:
male gen. Cydia conicolana ; female gen. Cydia conicolana