366 INJURIOUS AND BENEFICIAL INSECTS OP CALIFORNIA. 



pointed ovipositor, which pierces the body walls of the lice. The out- 

 side wound heals over in a shorl time, leaving the egg lightly sealed 

 within the body ready to hatch. As soon as the egg is hatched the 

 small, legless larva begins to feed upon the tissues of the aphid and 

 its development means the extinction of a louse. When it is fully 

 developed and ready to leave the "'mummied" louse, it cuts a circular 

 hole in the top of the body and escapes an adult winged insect, ready 

 to produce more eggs and thereby to destroy more lice. The life-cycle 

 varies according to the time of year. In the colder months it covers 

 from about ninety to one hundred days, while during the summer 

 months it covers from eight to fifteen days. It often does very good 

 work. 



The so-called "mummied" plant lice (Fig. 360) are easily recog- 

 nized before the adult parasite escapes, by the inflated and discolored 

 bodies which appear among the healthy individuals. These bodies are 

 usually of a lighter color and finally become greatly bleached. The 

 circular hole cut by the escaped parasite is always a sure sign of the 

 presence of this beneficial insect. The "mummies" are fastened to 

 the leaf, as soon as the louse is dead, by the larva of the parasite, 

 which cuts a slit in the lower side of the body and fastens the sides to 

 the leaf or twig by excreting a mucilaginous or weblike substance for 

 this purpose. 



Distribution. — This parasite is very common throughout the entire 

 State. 



Hosts. — It preys upon many of the common plant lice. So far it has 

 bred from the black citrus plant louse {Toxoptera auraniicv Koch), the 

 melon aphis (Aphis gossypii Glover) and the green apple aphis {Aphis 

 pomi De Geer). 



THE BLASTOPHAGA* 5 



Blastophaga psenes (Linnaeus) (Family Agaouida?) 



( Blastophaga grossorum Gravenhorst) 



(Cynips psehes Linnseus) 



(Fig. 364) 



Description. — The adults are exceedingly small, being about T Vj inch 

 long, the male being brown or amber and the female shiny black in 

 color. The female is winged, has large compound eyes and three 

 ocelli, ten-articled antenna?, well developed gnawing mouth-parts 

 and sharp ovipositor, which, when fully extended, is exceedingly long. 

 The male is always wingless, has small compound eyes and no ocelli. 

 The eggs are white, elliptical, with a short petiole and exceedingly 

 minute. The larva' are legless and white with brown mandibles. They 

 are exceedingly small. 



Life History and Work.— This very important beneficial insect is 

 propagated only in certain non-edible figs, known as caprifigs. In 

 these the females lay their eggs in the ovaries of the flowers, by pushing 

 the ovipositor down through the hollow style. The ovaries inhabited 

 by the larvae are called galls, as in them the insects feed and develop. 

 The males issue first and crawl about over the galls. With their power- 



2 'Tlic writer is indebted to Mr. G. P. Rixford, Bur. Plant Industry, U. S. Dept. 

 Agric, for this information regarding Blastophaga /incurs (Linn.) 



