Tuesday, September 18, 2012

Pest News for Week of September 17


From: Steve Frank, Extension Entomologist

Fall Pest Cleanup

Fall is a good time for nurseries and landscapers to consider dormant oil applications for spider mite and scale management. It is also a great time to scout for these critters. After leaves drop you can get good coverage of trunks and branches where scales and mites are overwintering. Scouting is also easy in the fall because scales are often overwintering in their adult, or near adult stages, which are (a little) larger and easier to see. Without leaves it is also much easier to see the scales. Trees that have scales should be examined in spring to determine if live scales are still present and if further treatment is necessary. The squish test will give you a good idea if scales are alive. If you squish some scales with your finger nail and juice comes out they are alive. If it is dry and crumbly they are dead. Most horticultural oils have a low and high rate listed that may even indicate that they should be used on growing or dormant trees respectively. On dormant deciduous trees you can safely use the high rate. 

As a side note, I have seen a lot of wax scale on conifers and broad leaf evergreen plants. I probably see them a lot because they stand out so much. Right now most are juveniles about half the size of the adults.

Rose Bud Caterpillars

This is not a species of caterpillar but several generalists that will feed on rose plants and particularly the buds. Tobacco bud worm and corn earworm are the most common culprits. They are active throughout the year and I found some on my knockout roses this week. This does not usually cause extreme damage but can reduce flowering if you have a lot of caterpillars present. 
There are many incidental and beautiful caterpillars out now such as the American dagger moth. I have catalogued some pictures and information on my blog: http://ecoipm.com/

From: David Orr, Extension Entomologist

Soldier Beetles on Flowers

The margined leatherback (Chauliognathus marginatus) is one of two soldier beetles commonly seen feeding on nectar and pollen on garden flowers in the late summer and early fall. Sometimes they can be quite numerous and cause concern for gardeners. However, they do not damage plants and can be considered beneficial. The adult of this beetle can be predatory on small insects such as aphids, while the larvae feed on ground-dwelling invertebrates such as slugs and insects. Occasionally, the larvae can be found inside of damaged produce such as tomatoes that have split from rainfall, or been opened up by caterpillars.

Adult margined soldier beetles have somewhat flattened bodies and soft, leathery wing covers rather than the hard covers found in many beetles. They can appear clumsy as they 'stumble' around flower heads on their long legs looking for both food and mates. Margined soldier beetle larvae look velvety and soft, and their legs are small and hard to see. This can make them appear similar to caterpillars. However, if you watch them carefully they have no legs near their rear end so they move by dragging their bodies along using the 3 pairs of legs under their thorax. Caterpillars, on the other hand, use either an "inchworm" or slinky type movement to lift up and bring their back legs closer to the front ones. 

For more information contact your local Cooperative Extension Center and ask for the Commercial Horticulture Agent.