Your tree may have two insects feeding on its leaves. The first is a leaf roller. It feeds inside their rolled together and tied with silk leaf nests. Bacterial products containing Bacillus thuringiensis (Bt) work against caterpillars when they are small and feeding. Your insects may to mature for Bt to work. Cut the caterpillars out of the rolled leaf and throw them into soapy water.
http://apps.extension.umn.edu/garden/diagnose/plant/fruit/apple/leavesrolled.html

The second insect in your pictures is called a pear sawfly or pear slug. Pear sawflies feed on hawthorn, service berry, pear, and other members of the rose family. Pear sawfly larvae are greenish black. The pear sawfly is a member of a group of insects sometimes called “slugs” because they superficially resemble true slugs. The Pear sawfly adult is a harmless wasp. Adult Pear sawflies emerge in late spring and lay their eggs on the underside of host plant leaves. Larvae appear several weeks later, feed on soft leaf tissue for about a month, and then drop into the soil to pupate. Pear slug larvae feed on the upper leaf surface. They avoid the larger leaf veins and rarely penetrate the lower leaf surface. The resultant “skeletonized” leaves have a characteristic appearance. Chewed areas of the leaf turn brown. A second generation can begin in late summer. Light infestations can be treated by simply picking off larvae by hand and throwing them into a bucket of soapy water. Pear slugs are easily killed with insecticidal soap, neem oil, bifenthrin, carbaryl, malathion, permethrin, spinosad or other general landscape insecticide sprays. Pear slugs are not controlled by bacterial products containing Bacillus thuringiensis (Bt). https://extension.colostate.edu/topic-areas/insects/pear-slugs-5-560/ Pick the leaf roller caterpillars off the plant and throw in into a container of soapy water.

The tree has a fungal disease related to cedar-apple rust.Cedar-apple rust related rust fungi need plants from two plant
families to complete their life cycle; Cupressaceae family (eastern red cedar and other junipers) and, serviceberry.These fungi rarely cause serious damage to their hosts and do not require management in most cases. Inspect nearby juniper and red cedar trees in late winter or earlyspring. Prune and remove brown, woody galls found before orange,gelatinous structures form in the spring. This will help reduce the level of infection on your nearby Service berry tree.  https://extension.umn.edu/plant-diseases/cedar-apple-rust