The insect Parasites of the Carrot Fly, Psila rosae, Fab.
Four insect parasites of the carrot fly have been encountered and of these three have been identified as Dacnusa gracilis, Loxotropa tritoma, and Aleochara sparsa. The fourth is a member of the genus Kleidotoma, species not yet ascertained.The life-history, development and host relations of D. gracilis and L. tritoma are given together with data on their distribution and range of parasitism.L. tritoma also occurs as a hyperparasite of D. gracilis but this appears to be quite fortuitous.Experimental evidence is brought forward to show that the first instar larva of L. tritoma goes into a diapause in early July, that a period at a low temperature is necessary to break this and hence development is only completed in the following spring.A description is given of the three larval stages of A. sparsa.Brief reference is made to the Kleidotoma sp. which appears to be of rare occurrence.