REPORT OF THE STATE ENTOMOLOGIST I9QI17 123 
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 
pupae 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 Pinus radiata. 
It also attacks the following species: P. tuberculata, P. 
miaricata PP sabiniana, P. coulter: andily 
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. T he 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 tne fascicles may 
be seriously injured, the leaves being mere rudiments of the normal 
structure. 
