44 



BtJLLETIlSr 4:21, V. S. DEPARTMENT OF AGRICULTURE. 



MICROCrASTER SP.' 



This, the most active parasite attacking the tuber moth, pre- 

 fers haK-grown leaf-mining larvae. This parasite seems the best 

 fitted naturally to be a dangerous enemy of the tuber moth, but dur- 

 ing three years' observation has not reached expectations. 



The adults (fig. 39) are readily reared at anytime from late summer to 

 spring, but never in large numbers. The adult has the shortest length 



of life of any observed. Even when fed, 

 only one individual lived as long as 11 days. 

 It seems to be fairly well distributed through 

 the San Gabriel Valley. 



The record of a typical life cycle follows : 



1915. 

 August 18. — Tuber-moth larvae parasitized by Micro- 



gaster sp. 

 September 3. — ] adult issued. (Male.) 

 September 4. — 2 adults issued. (Male and female.) 

 September 6. — 1 adult issued. (Male.) 

 Life cycle 16 days at an average temperature of 73° F. 



DIBRACHYS CLISIOCAMPAE FITCH. ^ 



Fig. 37.— Lateral view of mature 

 larva of Apanteles sp. (Chttn. 

 No. 22300'), with view of fan at 

 left below. Much enlarged. 

 (Original.) 



The last well-ascertained parasite of the 

 tuber moth was Dihrachys clisiocampae 

 Fitch. During 1913 one fe- 

 male was reared from tuber- 

 moth material, but could not be bred through, and as 

 no more issued, it was given up. 



In the winter of 1914 specimens were captured on 

 potato foliage, and it was later noticed breeding on 

 stored potatoes in the insectary. The parasite ovi- 

 posits in the mature larvge in cocoons, and in pupae 

 and issues from both stages, but usually from the 

 mature larvae. This parasite works both in the field 

 and in storage. It seems to prefer piles of potatoes, 

 working all through them, and also has been noted to 

 oviposit in dark bins. The egg is shown in figure 40. 

 The adult (fig. 41) is persistent, and if driven away 

 from a cocoon will return again and again until it ovi- 

 posits. Fourteen mature larvae (fig. 42) have been 

 reared from one host. These pupate (see fig. 43) with- 

 out spinning cocoons, and within the cocoon of their host. The 

 parasite does not seem to be very well distributed, having been 

 found only m Whittier and Pasadena, Cal. It seems at first glance 

 to be the most effective parasite of the tuber moth, but probably this 

 is not the case. It is not as effective a j others under field conditions, 



Fig. 38.— Apanteles 

 sp. (Chttn. No. 

 223007): Lateral 

 view of pupa. 

 Much enlarged. 

 (Origiaal.) 



1 Chittenden No. 223008. 



2 Chittenden No. 223009. 



