73 



reduced, however, if not lost entirely in dry portions of the field or in dry years, 

 or when fertilization of a naturally poor soil has been confined to the hill, as is so 

 often the case. In the case of squashes planted late, or having a slow early growth, 

 in which the runners have failed to root before the borers become half grown, the 

 crop is very often a failure. 



Natural Enemies. 



No parasitic enemies of the adult moth have yet been recorded. It is the chance 

 prey, however, of certain large robber flies (Asilidae) which have been observed to 

 pounce upon the moths in the fields. The larvae in their tunnels in the squash 

 stem appear to have escaped parasites, but are sometimes attacked by the larvae 

 and adults of ground beetles (Carabidae). These agencies are of little economic 

 importance. 



The eggs of the squash vine borer are subject to a high degree of parasitism by a 

 tiny wasp of the family Scelionidae, the members of which are exclusively egg 

 parasites. The species has been identified by Mr. A. B. Gahan, of the United 

 States National Museum, as Telenomus (Prophanurus) sp. The extent of the work 

 of this tiny benefactor is evident from the following records of rearings. 



Table III. — Parasitism of Squash Vine Borer Eggs. 



Control. 

 Cultural and Hand Methods. 



In.secticides have heretofore been considered useless in the control of the squash 

 vine borer, and consequently many cultural practises and hand methods have been 

 advanced for the purpose of lessening the severity of the attack. A few of these 

 are applicable under Massachusetts conditions, and are here discussed. 



Trap Crops. — Winter squash, summer squash, pumpkins, melons, and cucumbers 

 seem to be visited in the above order of preference by the egg-laying moths. Plant- 

 ings of winter squash or summer crooknecks may draw the moths away from other 

 cucurbits, and when used for this purpose should then be destroyed before the 

 borers in them become full grown. 



Fall Plowing. — Although many larvae doubtless penetrate below the plow 

 line before spinning their cocoons, others are turned up, crushed, or exposed to the 

 winter weather when squash fields are plowed in the fall following the removal 

 of the crop. 



Fertilization. — Many farmers seek to grow squashes on poor land with no appli- 

 cation of fertilizer except in the hill. Borer damage is sometimes greatly enhanced 

 by this practise. A note made by the writer in 1920 shows the effect of adequate 

 fertilization, and is here quoted: 



The history of the squash crop this year is a good illustration of the effect of proper 

 preparation of the land and care of the crop during early growth in offsetting the attack 

 of the squash vine borer. The experimental plot was a sandy loam. In the spring a 

 thirty-inch stand of rye had been plowed under. Lime was applied at the rate of three 

 thousand pounds per acre, and a 4-8-4 fertilizer at the rate of fifteen hundred pounds 



