?54 



INJURIOUS AND BENEFICIAL INSECTS OF CALIFORNIA. 



and after mating the females begin to insert their eggs in the tender 

 tips of the young shoots. The eggs hatch in a short time into larvae, 

 which work up the shoots until the latter are killed, when they turn 

 and go down the middle pith of the stems and transform in the late fall, 

 winter or early spring into pupae. There is one, or possibly two, broods 

 each year. 



Nature of Work.— The egg punctures near the tips of the young 

 shoots soon turn brown or black and are easily located. The new bur- 

 row, in the form of a spiral originating at the egg-puncture, and the 

 withered tip are sure evidences of the presence of the pest. In the 

 canes the burrows are made by the larvae down through the pith, nearly 

 to or into the roots. The adults cut a circular hole through the side 



Fig. 350. — Eggs of the raspberry horntail, Hartigia 

 cressoni (Kirby). Outer epidermis of tender shoot skinned 

 back to show the eggs in situ. (Author's illustration, Mo. 

 Bui. Cal. Hort. Com.) 



of the canes to escape. The principal damage is to the young shoots, 

 cutting off the main crop of blossoms and fruit. In some districts 

 50 to 90 per cent of the young shoots are thus killed at the tips. These 

 send up secondary shoots, which bear fewer, smaller and later berries. 



Distribution.— This horntail is widely distributed throughout the 

 Sacramento and San Joaquin valle3 r s and is especially destructive in 

 the Sierra foothills. 



Food Plants. — The native host of this insect is probably the wild 

 rose. Raspberries suffer most from the attacks. Cultivated roses, 

 blackberries and loganberries are also food plants. 



Control.— Measures necessary to remove or destroy the eggs before 

 the young larvae hatch should be inaugurated. As the eggs are very 



