REPORT OF THE STATE ENTOMOLOGIST I917 I23 



Thecodiplosis piniradiatae Snow & Mills 



1900 Snow, W. A. & Mills, Helen, Ent. News, 11:489-93 (Diplosis) 

 1900 Cannon, W. A. Amer. Nat., 34:801-10 (Diplosis) 



The midge discussed below represents a peculiar form approaching 

 the European Thurauia in the narrow wings and greatly reduced 

 circumfili, though separable therefrom by the structure of the male 

 genitalia, especially the terminal clasp segment, the ovipositor and 

 the triarticulate palpi. We tentatively referred this extreme form 

 to Thecodiplosis, despite the reduction in palpal segments. 



This species attacks the Monterey pine in California, causing a 

 shortening of the needles and a swelling at the base. This injury 

 was very noticeable in the autumn of 1897, and an examination of 

 the stunted, swollen needles revealed an Itonid larva at the very 

 base. The first adults were obtained in 1898 from affected branches 

 brought into the laboratory. 



Life history. The following is an abstract from Snow and Mills. 

 There appears to be but one generation annually. Adults begin to 

 issue about the middle of June and continue to appear until the 

 first of March. Egg laying proceeds during this entire period. The 

 ptipae are of the same general color as the larvae, the thoracic region 

 being dark. The body is covered with spinules as in 'the larvae. 

 The breathing tubes are nonsegmented and are slightly folded over 

 at the top. This species is not confined to P i n u s r a d i a t a. 

 It also attacks the following species: P. tuberculata, P. 

 muricata, P. sabiniana, P. coulteri and P. 

 sylvestris. All these pines are but slightly injured compared 

 with the Monterey pine. This species has been found abundant at 

 Stanford University and in small numbers at various places on the 

 San Francisco peninsula and in the Santa Clara valley. 



The female moves over the terminal buds, attempting at intervals 

 to thrust her long, flexible ovipositor between the scales, it sometimes 

 being bent like a bow. Two to 24 eggs are deposited in a mass, 

 about 2 weeks being required for them to hatch. Old larvae, pupae 

 or adults may be found from January into March. The newly 

 hatched larvae immediately make their way to the basal part of the 

 bud, remaining there through the summer and early winter and 

 not pupating until December. The adults issue a few weeks or 

 months later and the life cycle begins anew. 



The insect is so abundant that three-fourths of the fascicles may 

 be seriously injured, the leaves being mere rudiments of the normal 

 structure. 



